Method for the production of 18F-labeled active esters and their application exemplified by the preparation of a PSMA-specific PET-tracer

ABSTRACT

Novel efficient, time-saving and reliable radiofluorination procedures for the production of 18F-labelled active esters via nucleophilic substitution of the corresponding onium precursors with 18F− are described. The active ester including [18F]F-Py-TFP and [18F]TFB produced by one of these methods was used to prepare PSMA-specific PET tracers such as [18F]DCFPyL. The key advantages of these inventive methods are efficiency, short time of preparation and excellent amenability to automation. A pharmaceutical composition containing at least one PSMA-specific PET tracers prepared by the inventive method is useful for positron emission tomography (PET) imaging, especially imaging prostate tumor.

Novel efficient, time-saving and reliable radiofluorination proceduresfor the production of ¹⁸F-labeled active esters via nucleophilicsubstitution of the corresponding onium precursors with ¹⁸F⁻ aredescribed. The active ester including [¹⁸F]F-Py-TFP 3c and [¹⁸F]TFB 3aproduced by one of these methods was used to prepare PSMA-specific PETtracers such as [¹⁸F]DCFPyL 1-10. The key advantages of these inventivemethods are efficiency, short time of preparation and excellentamenability to automation. A pharmaceutical composition containing atleast one PSMA-specific PET tracers prepared by the inventive method isuseful for positron emission tomography (PET) imaging, especiallyimaging prostate tumor.

BACKGROUND OF THE INVENTION

Amongst imaging technologies PET (Positron Emission Tomography) plays avery important role due to its outstanding potential to visualizephysiological processes at the molecular level in real time. PET istherefore essential in clinical diagnostics and has gained majorsignificance in drug development. Beside technical improvements, PETbenefits mainly from innovations in the field of tracer development,comprising both progress in labelling strategies and an intelligentdesign of selective molecular probes with the capability to visualizemolecular targets involved in physiological and pathophysiologicalprocesses. A prerequisite for the latter is a deepened insight into thebiology underlying normal or diseased states at the molecular level.Molecular probes for PET-imaging must be labeled with suitableγ⁺-emitting nuclides. Among the spectrum of easy available radionuclides¹⁸F-fluorine is still the nuclide with the highest impact in PETresearch. This is mainly based on the excellent nuclear properties of¹⁸F in comparison to other cyclotron-produced nuclides. Decaycharacteristics of ¹⁸F [E(β⁺)=630 keV, abundance: 97%; t_(1/2)=109.8min] make it an ideal PET-isotope with respect to half-life andresolution.

Numerous methods for ¹⁸F labelling have been developed to preparetailor-made probes which allow visualizing biochemical processes ofinterest. The vast majority of ¹⁸F-labelling techniques are based onaliphatic and aromatic nucleophilic substitution reaction with ¹⁸F⁻.Sometimes, ¹⁸F-labeled small molecules can be obtained in one step fromthe proper labelling precursor. However, protecting groups are oftenrequired for functionalities in the molecule which may interfere withthe radiofluorination reaction.

Relatively harsh reaction conditions for radiofluorination are normallyincompatible with sensitive molecules including proteins and themajority of peptides. In this case indirect radiofluorination via¹⁸F-labeled prosthetic groups is the only alternative. Radiofluorinatedactive esters—amine-reactive prosthetic groups—are among the most widelyused radiolabeled building blocks.

In all previously described radiosyntheses of ¹⁸F-labelled active esters[¹⁸F]fluoride should be preliminary taken up in an aqueous oraqueous/organic solution of moderately strong or weak bases to give thecorresponding [¹⁸F]fluoride salt. Usually K, Cs or tetraalkylammoniumcarbonates/bicarbonates are used. In case of K salts aminopolyethers areroutinely added to enhance the nucleophilicity of ¹⁸F⁻. In case of Csand tetraalkylammonium salts enhancement of ¹⁸F⁻ nucleophilicity isachieved as a result of charge separation based on the great differencebetween the sizes of counter ions. However, active esters are limitedlystable under basic conditions. Consequently, a majority of themincluding N-succinimidyl 4-[¹⁸F]fluorobenzoate ([¹⁸F]SFB) could not beusually prepared in one step in acceptable RCYs. Only few of them suchas 6-[¹⁸F]fluoronicotinic acid 2,3,5,6-tetrafluorophenyl ester([¹⁸F]F-Py-TFP) could be prepared via direct radiofluorination.Furthermore, water substantially diminishes nucleophilicity of ¹⁸F⁻ dueto tenacious hydration. Consequently, water removal using repetitiveazeotropic drying with acetonitrile is usually mandatory.

[¹⁸F]SFB is most commonly used for the preparation of radiolabelledbiomolecules. However, its broad application is hampered by tediouspreparation procedures. Some of them are summarized in Table 1.

TABLE 1 Selected methods for the preparation of [¹⁸F]SFB. StepsPrecursor R Process Time [min] RCY [%] Ref 3

H     OEt 3-step, 3-pot, 3 separations (SPE & HPLC) 3-step, 2-pot, 2separations (SPE) 3-step, 1-pot, 1 separation (SPE) 80     78   60 30-35    41-51   44 1     2   3 OtBu 3-step, 2-pot, 2 68 34-38 4 separations(SPE) 2

— 2-step, 2-pot, 2 separations (SPEs or SPE & HPLC) 100 (for 2 SPE); 160(for SPE & HPLC) 30-40 5 G. Vaidyanathan, M. R. Zalutsky, Nucl. Med.Biol. 1992, 19, 275-281.; H. -J. Wester, K. Hamacher, G. Stocklin, Nucl.Med. Biol. 1996, 23, 365-372.; S. Guhlke, H. H. Coenen, G. Stöcklin,Appl. Radiat Isot. 1994, 45, 715-725.; E. D. Hostetler, W. B. Edwards,C. J. Anderson, M. J. Welch, J. Label. Compd. Radiopharm. 1999, 42,S720-S722.; M. Glaser, E. Årstad, S. K. Luthra, E. G. Robins, J. LabelCompd. Radiopharm. 2009, 52, 327-330.

All described [¹⁸F]SFB radiosyntheses consist of 2-3 reactions andmultiple operation steps. For example, according to Wester et al. (Nucl.Med. Biol. 1996, 23, 365-372) [¹⁸F]SFB was prepared via ethyl4-[¹⁸F]fluorobenzoate (Scheme 1).

Accordingly, ¹⁸F⁻ target water was added to a solution of K₂CO₃/K₂C₂O₄and K2.2.2 (Kryptofix 222) in aqueous MeCN. The solvent was removedunder reduced pressure in a flow of nitrogen and the residue was twotimes azeotropically dried by using MeCN. The residue was taken up in asolution of N,N,N-trimethyl-4-carbomethoxyanilinium triflate in DMSO.The reaction mixture was heated at 90-110° C. for 6 min. Thereafter, 1 MNaOH was added and the mixture was heated at the same temperature for afurther 10 min.

Afterwards, it was acidified with 1 M HCl and diluted with water. Theintermediate 4-[¹⁸F]fluorobenzoic acid was purified by SPE (solid phaseextraction) using polystyrene and cation exchange cartridges.Tetramethylammonium hydroxide was then added to the methanolic solutionof the intermediate and MeOH was removed under reduced pressure at 90°C. The residue was two times azeotropically dried by using MeCN. To theresidue a solution of TSTA (N,N,N′,N′-tetramethyl(succinimido)uroniumtetrafluoroborate) in MeCN was added and the mixture was heated at 90°C. for 2 min. [¹⁸F]SFB was finally isolated by SPE using a polystyreneresin.

Glaser et al. (J. Label Compd. Radiopharm. 2009, 52, 327-330) produced[¹⁸F]SFB via 4-[¹⁸F]fluorobenzaldehyde ([¹⁸F]FB-CHO) (Scheme 2). To asolution of K₂CO₃ and K2.2.2 in aqueous MeCN irradiated target water wasadded. The solvent was removed under reduced pressure in a flow ofnitrogen and the residue was three times azeotropically dried by usingMeCN. The residue was taken up in a solution ofN,N,N-trimethyl-4-formylanilinium triflate in DMSO or DMF. The reactionmixture was briefly heated using microwave energy. The mixture wastransferred on a silica gel cartridge and most of the solvent wasremoved by flushing with nitrogen. The intermediate [¹⁸F]FB-CHO wasfractionally eluted using anhydrous ethyl acetate. One fraction (0.5 mL)was cooled to 0 C. Iodobenzene diacetate (BAIB) was added, the mixturewas stirred at 0° C. for 15 min and allowed to reach ambient temperaturefor 5 min. It was decanted and the supernatant was purified via SPE orHPLC to afford [¹⁸F]SFB in EtOAc/hexane solution. Before [¹⁸F]SFB can beused for labelling of EtOAc/hexane-insoluble proteins or peptides, itshould be taken up in an water-miscible solvent.

Additionally, the high hydrophobicity of the fluorobenzoyl group limitsits application for the labelling of small molecules and shorterpeptides. Therefore, several alternatives to SFB were proposed. The mostinteresting one is 6-[¹⁸F]fluoronicotinic acid 2,3,5,6-tetrafluorophenylester ([¹⁸F]F-Py-TFP) first published by Olberg et al. (J. Med. Chem.2010, 53, 1732-1740). [¹⁸F]F-Py-TFP could be prepared using a one-stepprocedure in moderate radiochemical yield (RCYs) of 40-50% (Scheme 3).Additionally, [¹⁸F]F-Py-TFP is more hydrolytically stable compared to[¹⁸F]SFB. Moreover, it provides more hydrophilic radiolabelledconjugates.

According to Olberg et al. ¹⁸F⁻ was fixed on an anion exchange resin.Thereafter, it was eluted with a solution of tetrabutylammoniumbicarbonate in 50% MeCN. The solvent was removed under reduced pressurein a flow of nitrogen and the residue was two times azeotropically driedby using MeCN. After that, a solution of the respective precursor,N,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate 4c, in MeCN/tBuOH 2:8 was added to the[¹⁸F]TBAF and the reaction mixture was heated at 40 C for 10 min to give[¹⁸F]F-Py-TFP 3c in 50% RCY. [¹⁸F]F-Py-TFP was purified by SPE on amixed mode reversed phase cation exchange resin. This synthetic methodincludes azeotropic drying steps. These preparation steps cause longersynthesis time and this results in lower RCYs of [¹⁸F]F-Py-TFP 3c.Furthermore, formation of [¹⁸F]F-Py-TFP is accompanied by the concurrentformation of significant amounts of 2,3,5,6-tetrafluorophenyl6-(2,3,5,6-tetrafluorophenoxy)nicotinate which should be completelyseparated from the radiolabelled active ester best by HPLC.

In recent years imaging of prostate carcinoma (PCa) with PET isotopelabelled PSMA ligands has become of considerable importance in clinicaldiagnosis. This can be mainly attributed to the high expression of theextracellular localized prostate specific membrane antigen (PSMA) inPCa. Ligands bearing the syL-C(O)-Glu-binding motif exhibit high bindingaffinity to PSMA. Pomper et al. (WO2010/01493; Clin. Cancer Res. 2011,17, 7645-7653) exploited this lead structure to prepare2-(3-{1-carboxy-5-[(6-[¹⁸F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioicacid ([¹⁸F]DCFPyL) (Scheme 4). This PET tracer provided a cleardelineation of PSMA positive prostate tumor xenografts in mice with anexcellent tumor to background ratio.

Pomper et al. prepared [¹⁸F]DCFPyL in three steps. First, [¹⁸F]F-Py-TFPwas synthesized as reported by Olberg et al. (J. Med. Chem. 2010, 53,1732-1740). [¹⁸F]F-Py-TFP was eluted from the resin with dichloromethaneinto a vial containing 1,5-bis(4-methoxyphenyl)methyl2-[({6-amino-1-[(4-methoxyphenyl)methoxy]-1-oxohexan-2-yl}carbamoyl)amino]pentanedioate[H-DUPA(OPMB)₃] and triethylamine 11 (Scheme 4). The reaction mixturewas heated at 45° C. for 20 min. Thereafter the solvent was removed witha stream of nitrogen. Anisole in TFA was added, the reaction mixture washeated at 45° C. for further 10 min and the desired product was isolatedvia HPLC using 10% MeCN (0.1% TFA). The fraction containing [¹⁸F]DCFPyLwas neutralized with sodium bicarbonate, concentrated to dryness underreduced pressure and reconstituted in PBS to give [¹⁸F]DCFPyL in RCYs of50-65%. The disadvantages of the above-mentioned method are:

-   -   Application of dichloromethane as a solvent    -   Two evaporation steps    -   PMB deprotection step using toxic TFA (Scheme 4B step 3)    -   Neutralisation step    -   Formulation step

It is the objective of the present invention to provide an inventivemethod for preparation of PSMA selective PET tracer for prostate tumorimaging comprising a simplified procedure for the fast and high yieldingpreparation of ¹⁸F-labelled active esters and a pharmaceuticalcomposition containing at least one compound (I) prepared by theinventive method for use in positron emission tomography (PET) imaging,especially imaging prostate tumor.

The objective of the present invention is solved by the teaching of theindependent claims. Further advantageous features, aspects and detailsof the invention are evident from the dependent claims, the description,the figures, and the examples of the present application.

DESCRIPTION OF THE INVENTION

Accordingly the present invention relates to a method for preparing acompound of the general formula (I):

-   -   wherein A, B, C, and D represent independently of each other        C—H, C—F or N; and not more than two of A, B, C, and D represent        N;    -   E represents a covalent bond or

-   -    wherein    -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃        haloalkoxy, C₂-C₄ alkylcarbonyl, C₂-C₄ alkyloxycarbonyl, C₂-C₄        alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro;    -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10, preferably 0 to 5;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;    -   and diastereomers, enantiomers, hydrates, and salts thereof.

Further, the present invention relates to a method for preparing acompound of the general formula (I):

whereinA, B, C, and D represent independently of each other C—H, C—F or N;and not more than two of A, B, C, and D represent N;E represents a covalent bond or

-   -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₂-C₄ alkylcarbonyl,        C₂-C₄ alkyloxycarbonyl, C₂-C₄ alkylcarboxy, aryloxy,        arylcarboxy, cyano, or nitro;    -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10, preferably 0 to 5;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;        and diastereomers, enantiomers, hydrates, and salts thereof.

Still further, the present invention relates to a method for preparing acompound of the general formula (I):

wherein A, B, C, and D represent independently of each other C—H, C—F,C—Cl, or N; and not more than two of A, B, C, and D represent N;E represents a covalent bond or

wherein

-   -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃        thioalkyl, C₁-C₄ haloalkoxy, C₁-C₄ alkylcarbonyl, C₁-C₄        alkyloxycarbonyl, C₁-C₄ alkylcarboxy, aryloxy, alkylaryl, aryl,        arylcarboxy, halogen, preferably Cl or Br; trifluoromethyl,        perfluoroalkyl, cyano or nitro;    -   n is an integer selected from 0 to 10;    -   n₁ is an integer selected from 0 to 10;    -   n₂ is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10;    -   q is an integer selected from 1 to 18;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, NH—, or —N—;    -   represents a single or double bond;    -   and diastereomers, enantiomers, hydrates, and salts thereof.

The present invention further provides a method of preparing formula (I)as defined I the claims.

The present invention further provides a compound of formula (II):

wherein, E represents a covalent bond or

wherein

-   -   n is an integer selected from 0 to 10;    -   n₁ is an integer selected from 0 to 10;    -   n₂ is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10;    -   q is an integer selected from 1 to 18;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;    -   and diastereomers, enantiomers, hydrates, and salts thereof.

The invention also provides a compound of formula (II)

-   -   wherein, E represents a covalent bond or

-   -   wherein    -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;        and diastereomers, enantiomers, hydrates, and salts thereof.

In a further embodiment the above compounds (II) are direct precursorsof the compound of formula (I) as defined in any of the aboveembodiments, or they are used as direct precursors:

wherein A, B, C, and D represent independently of each other C—H, C—F,C—Cl, or N; and not more than two of A, B, C, and D represent N;E represents a covalent bond or

wherein

-   -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃        thioalkyl, C₁-C₄ haloalkoxy, C₁-C₄ alkylcarbonyl, C₁-C₄        alkyloxycarbonyl, C₁-C₄ alkylcarboxy, aryloxy, alkylaryl, aryl,        arylcarboxy, Cl, Br, trifluoromethyl, cyano or nitro;    -   n is an integer selected from 0 to 10;    -   n₁ is an integer selected from 0 to 10;    -   n₂ is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10;    -   q is an integer selected from 1 to 18;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH—, or —N—;    -   represents a single or double bond;        and diastereomers, enantiomers, hydrates, and salts thereof.

In further embodiments of the invention, the compound is a directprecursor of the compound of formula (I) or is used as direct precursor,wherein formula (I) is:

wherein A, B, C, and D represent independently of each other C—H, C—F orN; and not more than two of A, B, C, and D represent N;E represents a covalent bond or

whereinR¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃haloalkoxy, C₂-C₄ alkylcarbonyl, C₂-C₄ alkyloxycarbonyl, C₂-C₄alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro;n is an integer selected from 0 to 10;m is an integer selected from 1 to 18;X, Y, W, and Z represent independently of each other —CH₂—, —CH—, —NH—or —N—;

represents a single or double bond;and diastereomers, enantiomers, hydrates, and salts thereof.

In further embodiments of the invention either of n or n₁ or n₂ in theabove compounds (I) and/or (II) is an integer selected from 1-4, andpreferably n or n₁ or n₂ is an integer selected from 1 or 2 in anypossible combination.

In further embodiments of the invention m in the above compounds (I) and(II) is an integer selected from 1 to 10, and preferably m is an integerselected from 1 to 4 in any possible combination with any of thepreceding compounds.

In further embodiments of the invention in the above compounds (I) and(II) p is an integer selected from 0 to 6, and preferably p is aninteger selected from 0, 2 to 4 in any possible combination with any ofthe preceding compounds.

In further embodiments of the invention in the above compounds (I) and(II) q is an integer selected from 1 to 10, preferably q is an integerselected from 1 to 3 in any possible combination with any of thepreceding compounds.

In further embodiments of the invention a compound of formula (II) isselected from the group comprising compounds 2a-2p:

In further embodiments of the invention the compound of formula (I) or(II), the salt is selected from the group comprising acetate,trifluoroacetate, tosylate, mesylate, triflate, chloride, bromide,iodide, sulfate, hydrosulfate, nitrate, perchlorate, lithium, sodium,potassium, cesium, trialkylaryl-, tetraaryl-, tri- and tetralkylammoniumsalts.

Compounds of formula (II) can be prepared using procedures known in theart. In general, the materials used will be determined by the desiredstructure, and the type linkage used. Typically, the synthesis of thecompounds is started by the preparation of urea pharmacophore units,such as the lysine-urea-glutamate compounds, for example, as describedby Maresca et al. (J. Med. Chem., 2009, 52 (2), pp 347-357). Otherurea-glutamate based compounds may also be used as building blocks.Compounds II may be readily prepared by reactions between amines andactivated carboxylic acids or active esters, such as an acyl anhydrideand acyl halide or N-hydroxysuccinimide and 2,3,5,6-tetrafluorophenylester. Carboxylic acids may also be activated in situ, for example, withcoupling reagent, such as carbodiimides, benzotriazole-,7-azabenzotriazole-, succinimide-derived phosphonium and uronium salts,or carbonyldiimidazole (CDI). Active esters may be formed by reactionbetween alcohols and activated carboxylic acids.

Protecting groups may be used, if necessary, to protect reactive groupswhile the compounds are being assembled. Suitable protecting groups andconditions for their removal will be readily available to one ofordinary skill in the art. In this way, the compounds may be easilyprepared from individual building blocks, such as amines, carboxylicacids, and amino acids (see examples 15-18).

In further embodiments of the present invention, the direct precursor ofthe compound of formula (I) is suitable of being coupled to a compoundof formula (III), optionally in an anhydrous protic solvent, preferablyin a C₂-C₅ alcohol, preferably ethanol wherein formula (III) is

wherein A, B, C, D and R¹ have the meanings as defined above, andOL represents a leaving group, optionally wherein the residue L of theleaving group OL in formula (III) represents preferably:

and wherein R⁵ is selected from methyl, ethyl, or n-propyl, furtheroptionally wherein the compound (III) is selected from the groupcomprising:

The present invention relates also to a method of preparing a compound(III) comprising the following steps (A1)-(A8):

-   (A1) providing a solution of a compound of the formula (IV) in at    least one polar protic solvent or in a solvent mixture containing a    polar protic solvent,

-   -   wherein    -   A, B, C, D, OL and R¹ have the same meanings as defined above;    -   X represents NR² ₃, IR³, SR³ ₂;    -   Y represents Br, I, BF₄, O₂CCF₃, OSO₂CF₃, ClO₄, NO₂,        OSO₂C₆H₄CH₃, OSO₂CH₃;    -   R² represents C₁-C₄ alkyl; and    -   R³ represents aryl;

-   (A2) providing an aqueous solution of ^([18F])fluoride;

-   (A3) loading the aqueous solution of ^([18F])fluoride onto an anion    exchange resin;

-   (A4) washing the anion exchange resin with a polar protic solvent or    with a polar aprotic solvent;

-   (A5) flushing of the solvent with air or inert gas flow;

-   (A6) eluting of [¹⁸F]fluoride with the solution of the compound of    formula (IV) provided in step (A1), preferably in EtOH and diluting    of the resulting solution with an aprotic solvent or with at least    one C₃-C₆ alcohol or with a solvent mixture of at least one C₃-C₆    alcohol and an aprotic solvent, preferably with tBuOH/MeCN 1:4;    -   or    -   eluting of [¹⁸F]fluoride with the solution of the compound of        formula (IV) provided in step (A1), preferably in MeOH        concentrating of the resulting solution and redissolving of the        residue in an aprotic solvent, preferably in DMSO;

-   (A7) allowing the compound of formula (IV) to react with    [¹⁸F]fluoride in order to obtain the compound of the formula (III);

-   -   wherein A, B, C, D, OL and R¹ have the same meanings as defined        above; and

-   (A8) purifying of the compound of formula (III).

The present invention also relates to the use of a compound of formula(II) as defined in any of the foregoing paragraphs in the preparation ofcompound (I) as defined above.

The present invention also relates to a method for preparing a compoundof formula (I) as defined above,

comprising the steps:

-   (A) providing a solution of a compound of formula (II) as defined    above in a polar protic solvent, preferably in EtOH, or in a solvent    mixture containing a polar protic solvent containing at least one    base, preferably in Et₄NHCO₃;

-   (B) providing a solution of a compound of formula (III) as defined    above

-   -   in a polar protic solvent, preferably in EtOH, or in a solvent        mixture containing a polar protic solvent;

-   (C) mixing the solution of the compound of formula (II) and the    solution of the compound of formula (III) and allowing the compound    of formula (II) to react with the compound of formula (III) in order    to obtain the compound of formula (I),

-   (D) purifying the compound of formula (I), preferably by using    isotonic sodium chloride solution.

The present invention also relates to a method as defined above, whereinstep (C) is performed at a reaction temperature T2 which is in the rangeof 30° C. to 60° C., preferably 20° to 60° C., wherein the reaction timet2 of step (C) is optionally 1-30 min, and wherein the pH value of thereaction solution in step (C) is optionally in the range of 7.0-11.0.

The present invention also relates to a method as defined above, whereinthe compound of formula (III) does not require purification via HPLC,

and/or wherein the method does not comprise the application of a baseand any other additives such as commonly known activating compounds suchas Kryptofix or 18-crown-6 or other substances known in the art; and/orwherein the method comprises the application of only onium saltprecursor (IV) and ^([18F])fluoride; and/or wherein the method does notcomprise any azeotropic drying steps; and/or wherein the method does notrequire any evaporation steps.

The present invention also relates to a method as defined above, whereinthe compound of formula (I) does not require purification via HPLC, andwherein the method comprises the application of environmentally benignsolvents such as ethanol (rather than dichlormethane or acetonitrilethat are used, e.g. according to the method of Pomper/Mease); and/orwherein the method does not comprise any evaporation steps; and/orwherein the method does not require any deprotection steps, wherein saiddeprotection steps may be steps of p-methoxybenzyl (PMB) or tBudeprotection using anisol/TFA mixture; and/or wherein the method doesnot require a neutralization step (such as described according to themethod of Pomper/Mease); and/or wherein the method does not require aformulation step.

The use of toxic solvents is a particular disadvantage of methods of theprior art and is avoided in the inventive methods. The present inventiondoes not require the use of toxic solvents, e.g. dichloromethane oracetonitrile.

The present invention also relates to a method as defined above furthercomprising the following step (E) after the step (D), wherein step (E)is the sterilization of the solution of the compound of formula (I) viasterile filtration.

The present invention also relates to a method as defined above furthercomprising steps (A1)-(A8) as defined above after step (A) and beforestep (B).

The present invention also relates to a method as defined above furthercomprising the following step (F) after the step (D) or (E): (F)preparing a pharmaceutical composition containing the solution of thecompound of formula (I).

The present invention also relates to a method as defined above, whereinthe base in step (A) is an organic nitrogen-containing base or abicarbonate, wherein the bicarbonate is preferably a quaternary ammoniumbicarbonate or hydrogenphosphate.

The present invention also relates to a method as defined above, whereinthe organic nitrogen-containing base or the bicarbonate is selected fromthe group comprising: LiHCO₃, NaHCO₃, KHCO₃, CsHCO₃, Me₄NHCO₃, Me₄NHPO₄,Et₄NHCO₃, Et₄NHPO₄, n-Pr₄NHCO₃, n-Pr₄NHPO₄, i-Pr₄NHCO₃, n-Bu₄NHCO₃,n-Bu₄NHPO₄, BzlMe₃NHCO₃, BzlMe₃NHPO₄, BzlEt₃NHCO₃, BzlEt₃NHPO₄,BzlBu₃NHCO₃, BzlBu₃NHPO₄, Et₃N, pyridine, lutidine, collidine,diisopropylethylamine, n-Pr₃N, i-Pr₃N, n-Bu₃N, i-Bu₃N,Oct₃N,N-methyl-morpholine, N-ethylmorpholine, N-methylpiperidine,N-ethylpiperidine, N,N-dicyclohexylmethylamineN,N-dimethylcyclohexylamine, N-methyl-dibutylamine,N-ethyldicyclohexylamine, N,N-dimethylbutylamine, andN,N-dimethylhexylamine.

The present invention also relates to a method as defined above, whereinthe [¹⁸F]fluoride is trapped on an anion exchange resin and then eluteddirectly.

The present invention also relates to a method as defined above, whereinthe C₃-C₆ alcohol is tBuOH.

The present invention also relates to a method as defined above, whereinthe compound of the formula (I) is selected from the group consisting ofcompounds 1-3, 1-10, 1-14, 1-17, 1-29, 1-31, 1-32, 1-33, and 1-34:

The inventive method for preparing the compounds of the general formula(I) may also comprise the following steps:

-   (A) providing a solution of a compound of formula (II) in a polar    protic solvent or in a solvent mixture containing a polar protic    solvent containing at least one base

-   -   wherein    -   E represents a covalent bond or

R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃haloalkoxy, C₂-C₄ alkylcarbonyl, C₂-C₄ alkyloxycarbonyl, C₂-C₄alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro;

-   -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10, preferably 0 to 5;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;

-   (B) providing a solution of a compound of formula (III)

-   -   wherein    -   A, B, C, D and R¹ have the meanings as defined above, and    -   OL represents a leaving group    -   in a polar protic solvent or in a solvent mixture containing a        polar protic solvent;

-   (C) mixing the solution of the compound of formula (II) and the    solution of the compound of formula (III) and allowing the compound    of formula (II) to react with the compound of formula (III) in order    to obtain the compound of formula (I);

-   (D) purifying the compound of formula (I) preferably by using saline    (which is isotonic sodium chloride solution).

The residue L of the leaving group OL represents preferably:

and wherein R⁵ is selected from methyl, ethyl, or n-propyl.

It is also preferred if A or B or C or D is nitrogen and the othersubstituents are CH or CF. More preferred are compounds wherein A and Bare nitrogen and C and D are CH or CF or wherein B and C are nitrogenand A and D are CH or CF or wherein C and D are nitrogen and A and B areCH or CF or wherein A and D are nitrogen and B and C are CH or CF orwherein A and C are nitrogen and B and D are CH or CF or wherein B and Dare nitrogen and A and C are CH or CF or wherein A, B, C, D are CH orwherein A, B, C, D are CF.

Further preferred are compounds wherein the moiety

contains an aromatic nitrogen heterocyclic ring wherein one of X, Y, W,and Z is nitrogen and the other substituents are CH, or wherein X and Yor W and Z or X and W or Z and Y or X and Z or W and Y are nitrogen andthe other two substituents are CH.p is preferably selected from 0, 1, 2, 3, 4 and 5, more preferably from0, 1, 2, 3 and 4, still more preferably from 0, 1, 2 and 3, still morepreferably from 0, 1 and 2, and most preferably from 0 and 1.

An embodiment of the present invention refers to any one of theabove-described methods, wherein the base of step (A) is an organicnitrogen-containing base or a bicarbonate. The organicnitrogen-containing base is preferably a monoalkylamine, dialkylamine,trialkylamine or an ammonium base, especially a tetraalkylammonium baseand more preferably a trialkylamine or tetraalkylammonium base, whereinthe term “trialkylamine” and the term “tetraalkylammonium” covers alsocyclic amines and cyclic ammonium ions such as N-ethylmorpholine andN-methylpiperidine. Said organic nitrogen-containing base or saidbicarbonate is preferably selected from the group comprising orconsisting of: Me₄NHCO₃, Et₄NHCO₃, n-Pr₄NHCO₃, i-Pr₄NHCO₃, n-Bu₄NHCO₃,i-Bu₄NHCO₃, Et₃N, pyridine, lutidine, collidine, diisopropylethylamine,n-Pr₃N, i-Pr₃N, n-Bu₃N, i-Bu₃N, Oct₃N, N-methyl-morpholine,N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine,N,N-dicyclohexylmethylamine, N,N-dimethylcyclohexylamine,N-methyldibutylamine, N-ethyldicyclohexylamine, N,N-dimethylbutylamine,and N,N-dimethylhexylamine. Said bicarbonate may be selected from thegroup comprising or consisting of: LiHCO₃, NaHCO₃, KHCO₃, CsHCO₃,Me₄NHCO₃, Et₄NHCO₃, n-Pr₄NHCO₃, and n-Bu₄NHCO₃; and preferably fromMe₄NHCO₃, Et₄NHCO₃, n-Pr₄NHCO₃, and n-Bu₄NHCO₃ or may be as definedabove.

In one embodiment of the present invention, said method comprising thestep (C), wherein step (C) is performed at a reaction temperature T2which is in the range of 20° C. to 130° C., preferred 20° C. to 100° C.,more preferred more preferred 30° C. to 80° C., most preferred 20° C. to600 or 30° C.-60° C. and during a reaction time t2 which is in the rangeof 0.1-40 min, preferred 0.1-30 min, more preferred 0.5-15 min, mostpreferred 1-10 min and at a pH value of the reaction solution which isin the range of 7.0 to 11.0. More preferably step (C) is performedduring a reaction time t2 of 1 to 5 minutes at a pH value of 7.0 to11.0. Still more preferably step (C) is performed during a reaction timet2 of 1 to 5 minutes at a pH value of 7.0 to 11.0 and at a reactiontemperature T2 in the range of 20° C. to 80° C. and more preferably inthe range of 30° C. to 60° C.

In the step (D), the compound of the formula (I) is preferred purifed bypreparative HPLC. As eluent saline may be suitable for purifying thecompound of the formula (I). Said saline is preferred isotonic sodiumchloride solution containing 0.90% (weight/volume, 9 g/1000 mL) ofsodium chloride. Optionally, said saline may further contains 5-15%(volume/volume) of EtOH.

Alternatively, phosphate buffered solution can be used for purifying thecompound of the formula (I). The phosphate buffered solution usuallycomprises sodiumphosphate, potassium phosphate and/or phosphoric acid.Optionally said phosphate buffered solution further comprises sodiumchloride and/or potassium chloride. Preferred, the osmolarity and ionconcentration of said phosphate buffered solution match those of thehuman body (isotonic). The pH value of said phosphate buffered solutionis in the range of 2.0 to 9.0, preferred 4.0 to 8.0, more preferred 6.0to 8.0 and most preferred 7.0 to 7.8. For example, PBS (phosphatebuffered saline) can be used for purifying the compound of the formula(I).

This purification step is a technical advantage compared with the priorart. In the prior art as shown in scheme 4, the HPLC purification wasperformed by using an aqueous eluent containing toxic acetonitrile andtrifluoroacetic acid (TFA). Thus, the solution of the purified compoundis not suitable for direct use for PET imaging. The toxic solventsshould be firstly removed and the compound residue should be redissolvedin the appropriate buffer solution. In contrast, in according to thepresent invention the resulting isotonic solution of the purifiedcompound of the formula (I) after the step (D) is ready for application.

Reverse phase column having a good hydrophobic retention and selectivitymay be suitable for the purification (e.g. Synergi 4 μm Hydro-RP 80 Å100×21.2 mm). The phase should be good suitable for the separation ofhigh polar hydrophilic compounds. Retention time should preferentiallybe less than 10 min by flow rate which is less than 10 mL/min.

In one embodiment of the present invention, any one of theabove-mentioned methods further comprises the following step (E) afterthe step (D):

-   (E) sterilizing the solution of the compound of formula (I) via    sterile filtration.

In one embodiment of the present invention, any one of theabove-mentioned methods further comprises the following steps (A1)-(A8)after step (A) and before step (B):

-   (A1) providing a solution of a compound of formula (IV) in at least    one polar protic solvent or in a solvent mixture containing a polar    protic solvent,    -   wherein optionally the solution further contains a salt;

-   -   wherein    -   A, B, C, D, L (or OL) and R¹ have the same meanings as defined        above;    -   X represents NR² ₃, IR³, SR³ ₂;    -   Y represents Br, I, BF₄, O₂CCF₃, OSO₂CF₃, ClO₄, NO₂,        OSO₂C₆H₄CH₃, OSO₂CH₃;    -   R² represents C₁-C₄ alkyl; and    -   R³ represents aryl;

-   (A2) providing an aqueous solution of [¹⁸F]fluoride (irradiated    [¹⁸O]water);

-   (A3) loading an aqueous solution of [¹⁸F]fluoride onto an anion    exchange resin;

-   (A4) washing the anion exchange resin with a polar protic solvent or    with a polar aprotic solvent;

-   (A5) flushing of the solvent with air or inert gas flow;

-   (A6) Eluting of [¹⁸F]fluoride with the solution of the compound of    the formula (IV) provided in the step (A1) and diluting of the    resulting solution with an aprotic solvent or with at least one    C₃-C₆ alcohol or with a solvent mixture of at least one C₃-C₆    alcohol and an aprotic solvent; or    -   eluting of [¹⁸F]fluoride with the solution of the compound of        the formula (IV) provided in the step (A1), concentrating of the        resulting solution and redissolving of the residue in an aprotic        solvent;

-   (A7) allowing the compound of formula (IV) to react with    [¹⁸F]fluoride in order to obtain the compound of the formula (III);

-   -   wherein A, B, C, D, L (or OL) and R¹ have the same meanings as        defined above; and

-   (A8) purifying of the compound of the formula (III).

An embodiment of the present invention refers to the above-describedinventive method, wherein said polar protic solvent is an anhydrouspolar protic solvent, preferably an anhydrous C₁-C₄ alcohol, diols suchas 1,4-butanediol or glycols such as diglycol, triglycol or tetraglycol,and especially anhydrous MeOH or anhydrous EtOH or a mixture thereof.

The use of an anhydrous protic solvent is advantageous in the steps(A)-(C) of the inventive method, because the presence of water preventsor impedes coupling reaction between the compound of the formula (II)and the compound of the formula (III). In the presence of water, theactive esters of formula (III) having a leaving group —O-L may reactwith water and form an undesired product i.e. the correspondingcarboxylic acid. This results in lower yield of the compound of theformula (I).

For the same reason, in the steps (A1)-(A7), said polar protic solventis preferably an anhydrous polar protic solvent, more preferred ananhydrous C₁-C₄ alcohol, diols such as 1,4-butanediol or glycols such asdiglycol (HO—C₂H₄—O—C₂H₄—OH), triglycol (HO—C₂H₄—O—C₂H₄—O—C₂H₄—OH) ortetraglycol (HO—C₂H₄—O—C₂H₄—O—C₂H₄—O—C₂H₄—OH), and especially anhydrousMeOH or anhydrous EtOH or a mixture thereof. In the steps (A1)-(A7), thepresence of water prevents or impedes a nucleophilic aromaticsubstitution reaction of ¹⁸F⁻ and results in a poor yield of thecompound of formula (III).

Said salt in step (A1) is preferably a bicarbonate salt and morepreferred selected from the group consisting of Me₄NHCO₃, Et₄NHCO₃,n-Pr₄NHCO₃, i-Pr₄NHCO₃, n-Bu₄NHCO₃ and i-Bu₄NHCO₃.

In the steps (A3) and (A4), said anion exchange resin is preferred asilica-based hydrophilic resin or polystyrene-based copolymer containingcarbonate or bicarbonate as counter anion and contained in a cartridgeFor example, commercially available Sep-Pak Accell Plus QMA carbonateplus light cartridges from Waters GmbH (Eschborn, Germany) andChromafixR 30-PS—HCO₃. cartridges from Macherey-Nagel (Duren, Germany)can be used.

In the steps (A4) and (A6), said polar aprotic solvent or said aproticsolvent is preferred MeCN or DMSO and said C₃-C₆ alcohol is preferredt-BuOH.

In the step (A7), the compound of the formula (IV) reacts with[¹⁸F]fluoride in a reaction time in the range of 1-20 min, preferred1-15 min, more preferred 5-10 min at the reaction temperature in therange of 20° C. to 140° C., preferred 30° C.-130° C., more preferred 40°C.-130° C. After the reaction is finished, the reaction mixture ispreferred cooled to a temperature in the range of 15 C-30° C. by aircooling.

In the step (A8), purifying of the compound of formula (III) isperformed via HPLC or solid phase extraction (SPE). HPLC purificationcan be carried out using, for example, polymer-based RP columns such asChromolith SpeedRod or RP C18 or C8 columns like Luna-2 or Nucleosil.SPE purification can be carried out using, for example, Strata X orSep-Pak C18 cartridges.

In one embodiment of the present invention, any one of theabove-described methods further comprises the following step (F) afterthe step (D) or (E):

-   (F) preparing a pharmaceutical composition containing the solution    of the compound of formula (I).

The compound of the formula (II) may have a good affinity toprostate-specific membrane antigen (PSMA).

Preferred, a compound of the formula (II) is selected from the compounds2a-2p:

Preferred, a compound of the formula (IV) having any of the subformulae(IV-1)-(IV-5) is used in the above-mentioned step (A1) of the inventivemethod:

wherein L, R¹, X and Y have the same meanings as defined above.

Also preferred, a compound of the formula (IV) having any one of thesubformulae (IV-6)-(IV-17) is used in the above-mentioned step (A1) ofthe inventive method:

wherein L, X and Y have the same meanings as defined above.

Most preferred, a compound of the formula (IV) selected from thefollowing compounds 4a-4f is used in the above-mentioned step (A1) ofthe inventive method:

Preferred, a compound of the formula (III) having any of the subformulae(III-1)-(III-5) which derived from a compound of any of the subformulae(IV-1)-(IV-5), is obtained from the above-mentioned steps (A7) and (A8)or used in the above-mentioned step (B) of the inventive method:

wherein L and R¹ have the same meanings as defined above.

Also preferred, a compound of the formula (III) having any of thesubformulae (III-6)-(III-17) which derived from a compound of any of thesubformulae (IV-6)-(IV-17), is obtained from the above-mentioned steps(A7) and (A8) or used in the above-mentioned step (B) of the inventivemethod:

wherein L has the same meanings as defined above.

Most preferred, a compound of the formula (III) selected from the groupconsisting of the following compound 3a-3f derived from compounds 4a-4f,is obtained from the above-mentioned steps (A7) and (A8) or used in theabove-mentioned step (B) of the inventive method:

The term “C₁-C₃ alkyl” as used herein refers to a saturated linear orbranched carbon chain consisting of 1-4 carbon atoms. Examples are —CH₃,—C₂H₅, —C₃H₇, and —CH(CH₃)₂.

The term “C₁-C₃ alkoxy” as used herein refers to a C₁-C₃ alkyl groupsingular bonded to oxygen and said C₁-C₃ alkyl has the same meaning asdefined above. Examples are —OCH₃, —OC₂H₅, —OC₃H₇, —OCH(CH₃)₂.

The term “C₁-C₃ haloalkyl” as used herein refers to a saturated linearor branched carbon chain consisting of 1 to 4 carbon atoms substitutedby at least one halogen atom such as F, Br, Cl and I. It is clear to askilled person that the term “substituted” refers to the replacement ofa hydrogen atom by one of the substituents. Examples of a C₁-C₃haloalkyl are —CH₂F, —CHF₂, —CF₃, —CCl₃, —CH₂CF₃, —C₂F₅, —C₃F₇,—CH(CF₃)₂.

The term “C₁-C₃ haloalkoxy” as used herein refers to a C₁-C₃ haloalkylgroup singular bonded to oxygen and said C₁-C₃ haloalkyl group has thesame meaning as defined above. Examples are —OCH₂F, —OCHF₂, —OCF₃,—OCCl₃, —OCH₂CF₃, —OC₂F₅, —OC₃F₇, —OCH(CF₃)₂.

The terms “C₁-C₄ alkylcarbonyl” and “C₂-C₄ alkylcarbonyl” as used hereinrefer preferably to a C₁-C₃ alkyl group singular bonded to carboxy groupand said C₁-C₃ alkyl has the same meaning as defined above. Examples are—COCH₃, —COC₂H₅, —COC₃H₇, —COCH(CH₃)₂.

The terms “C₁-C₄ alkylcarboxy” and “C₂-C₄ alkylcarboxy” as used hereinrefer preferably to a C₁-C₃ alkyl group singular bonded to carboxy group(—CO₂—) and said C₁-C₃ alkyl has the same meaning as defined above.Examples are —O₂CCH₃, —O₂CC₂H₅, —O₂CC₃H₇, —O₂CCH(CH₃)₂.

The terms “C₁-C₄ alkyloxycarbonyl” and “C₂-C₄ alkyloxycarbonyl” hereinrefers to a a C₁-C₃ alkyl group singular bonded to oxy carbonyl group(—O—CO—) and said C₁-C₃ alkyl has the same meaning as defined above.Examples are —CO₂CH₃, —CO₂C₂H₅, —CO₂C₃H₇, —CO₂CH(CH₃)₂.

The terms “aryl” as used herein refer to carbocyclic aromatic orheterocyclic aromatic residues or more specific to “C₆-C₁₀ carbocyclicaromatic residues with one or two aromatic rings and refers preferablyto phenyl and naphthyl, wherein these aromatic or heteroaryl residues,preferred phenyl, thienyl and naphthyl residues can be substituted with1 to 5 substituents selected from halogen like —F, —Br, —Cl, —I, C₁-C₃alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy, —CN, —OH, —NO₂,—CO₂(C₁-C₃ alkyl), —NHCO(C₁-C₃ alkyl), —NH(C₁-C₃ alkyl), —N(C₁-C₃alkyl)₂. It is clear to a skilled person that the term “can besubstituted” refers to the replacement of a hydrogen atom by one of thesaid substituents. The carbon atom number of C₆-C₁₀ refers only to thecarbon atoms of the aromatic ring system (aryl) and does not include thecarbon atoms of the said substituents. Examples are

The term “aryloxy” as used herein refers to a aryl group singular bondedto oxygen and said aryl has the same meaning as defined above.

The term “arylcarboxy” as used herein refers to a aryl group singularbonded to carbonyl group (—CO₂—) and said aryl has the same meaning asdefined above.

¹⁸F-Production

[¹⁸F]Fluoride was produced via the ¹⁸O(p,n)¹⁸F reaction by bombardmentof enriched [¹⁸O]water with protons using a 16 MeV cyclotron.

Preferred, the [¹⁸F]fluoride is trapped on an anion exchange resin. Theresin was washed with alcohol (e.g., with nPrOH, iPrOH, nBuOH, betterwith EtOH or MeOH) and drained with flow of gas (e.g., air, Ar, N₂, He).In the said method ¹⁸F⁻ is directly eluted with an alcoholic solution(e.g., in nPrOH, iPrOH, nBuOH, better in EtOH or MeOH) of thecorresponding onium precursor (e.g., ONP or OTFP). Alternatively, ¹⁸F⁻was eluted with an alcoholic solution (e.g., in nPrOH, iPrOH, nBuOH,better in EtOH or MeOH) of suitable salt, most preferablytetraethylammonium bicarbonate.

The term “C₁-C₄ alcohol” as used herein refers to a saturated linear,branched or cyclic C₁-C₄ alkyl group substituted by at least onehydroxyl group. It is clear to a skilled person that the term“substituted” refers to the replacement of a hydrogen atom by one of thesubstituents. Examples of a C₁-C₄ alcohol are CH₃OH, CH₃CH₂OH,HOCH₂CH₂OH, CH₃CH₂CH₂OH, HOCH₂CH₂CH₂OH, HOCH₂CH(OH)CH₃,HOCH₂CH(OH)CH₂OH, (CH₃)₂CHOH, CH₃CH₂CH₂CH₂OH, CH₃CH₂CH(OH)CH₂OH,CH₃CH(OH)CH₂CH₂OH, CH₂(OH)CH₂CH₂CH₂OH, CH₂(OH)CH(OH)CH₂CH₂OH,CH₃CH(OH)CH(OH)CH₂OH, CH₂(OH)CH(OH)CH(OH)CH₂OH, (CH₃)₂CHCH₂OH,H₃CCH(CH₂OH)₂, HC(CH₂OH)₃, and (CH₃)₃C—OH. Preferred, CH₃OH or CH₃CH₂OHis used as the C₁-C₄ alcohol in the above-described method.

The term “C₃-C₆ alcohol” as used herein refers to a saturated linear,branched or cyclic C₃-C₆ alkyl group substituted by at least onehydroxyl group. It is clear to a skilled person that the term“substituted” refers to the replacement of a hydrogen atom by one of thesubstituents. Preferred examples of a C₃-C₆ alcohol are CH₃CH₂CH₂OH,(CH₃)₂CHOH, CH₃CH₂CH₂CH₂OH, (CH₃)₂CHCH₂OH, (CH₃)₃C—OH,CH₃CH₂CH₂CH₂CH₂OH, (CH₃)₂CHCH₂CH₂OH, CH₃CH₂CH₂CH₂CH₂CH₂OH,(CH₃)₂CHCH₂CH₂CH₂OH, HOCH₂CH₂CH₂OH.

In an embodiment of the present invention, t-BuOH ((CH₃)₃C—OH) is usedas the C₃-C₆ alcohol in the above-described method.

The term “aprotic solvent” or “polar aprotic solvent” as used hereinrefers to acetone, DMF, DMA, 1,2-dimethoxyethane (glyme), MeCN,2-methoxyethyl ether (diglyme), N-methylpyrrolidinone, DMSO, sulfolane,propylenecarbonate, or THF. Preferred, MeCN, and DMSO are used.

The term “polar protic solvent” as used herein refers to any solventthat contains labile H⁺ and readily donate protons (H⁺) to reagents andcapable of dissolve the salts. Preferred examples of a polar proticsolvent are MeOH, EtOH, n-PrOH, i-PrOH, n-BuOH, HOCH₂CH₂OH,HOCH₂CH₂CH₂OH, HOCH₂CH(OH)CH₃, HOCH₂CH(OH)CH₂OH, HC(CH₂OH)₃,HO—C₂H₄—O—C₂H₄—OH, HO—C₂H₄—O—C₂H₄—O—C₂H₄—OH,HO—C₂H₄—O—C₂H₄—O—C₂H₄—O—C₂H₄—OH, HCO₂H and CH₃CO₂H.

In an embodiment of the present invention, EtOH is used as the polarprotic solvent in the above described method.

The term “RCY (radiochemical yield)” as used herein refers to the yieldfor the step in which the radiolabel is introduced. The RCY refers tothe activity (decy-corrected) of the radiolabel led product expressed asa fraction of the activity originally present.

The term “direct precursor” as used herein indicates that the respectivecompound can be used without protecting groups in the preparation of acompound according to formula (I) as defined herein. The term “directprecursor” means also that it can be used in the preparation in vitroof, e.g., ¹⁸F-labelled active esters that can be used as PET tracer,expecially in the preparation of compound according to formula (I) asdefined herein, which can be used as active ingredients inpharmaceutical compositions for use in PET imaging, for example in theimaging of tumors such as tumors of the prostate.

Preferred is said method for preparing a compound of any of the formulae(Ia)-(Ie):

wherein m is an integer from 1 to 8; p is an integer from 0 to 2.

Also preferred is said method for preparing a compound of the formula(I) selected from the compounds of the following subformulae(I-1)-(I-6):

More preferred is said method for preparing a compound of the formula(I) selected from the compounds of the following subformulae(I-6)-(I-15):

Still more preferred is said method for preparing a compound of theformula (I) selected from the following compounds 1-1-1-34.

Most preferred is said method for preparing the compound of the formula(I) selected from the group consisting of compounds 1-3, 1-10, 1-14,1-17, 1-29, 1-31, 1-32, 1-33, and 1-34:

The present invention refers to the compound of the formula (I)obtainable by any of the above mentioned inventive methods, preferablythe compound of any of the subformulae (Ia)-(Ie) and (I-1)-(I-15)obtainable by any of said inventive methods, more preferably thecompounds 1-1-1-34 obtainable by any of said inventive methods.

In the present invention, compound of the formula (III) as activatedaromatic ester (pyridine, pyrazine, pyrimidine, tri/tetrahalo, cyano-,nitro-, (per)fluoralkyl-, like trifluoromethyl-, alkylcarboxybenzene orsimilar) can be prepared by S_(N) _(Ar) radiofluorination of precursorcompound of the formula (IV) as shown in Scheme 5.

In case of less activated precursors of the formulae IV-6 and IV-7,e.g.,(4-methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodaniumperchlorate 2,3,5,6-tetrafluorophenyl 4-(4-methoxyphenyl)phenyliodoniumbenzoate perchlorate (4a), the solvent should be removed under reducedpressure before the nucleophilic reaction can be carried out. Theresidue is taken up in a suitable solvent and subsequently heated for ashort time to give the desired radiolabelled active ester as shownScheme 5A.

In case of highly activated precursors of the formulae IV-8-IV-17, e.g.N,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate (4c), removal of alcohol (except MeOH) isunnecessary. Accordingly, the ¹⁸F-eluate can be simply diluted with thecorresponding solvent (e.g., tBuOH, tBuOH/MeCN, MeCN, etc.) and directlyheated for a short time. Finally, the radiolabelled active esters areisolated using HPLC or SPE. In both cases neither azeotropic drying norbase nor any other additives are necessary (Scheme 5B). The describedmethods allow to prepare e. g., [¹⁸F]TFB 3a and [¹⁸F]F-Py-TFP 3c in20-25% and 90-94% RCYs, respectively. Alternatively, ¹⁸F-labelled activeesters from highly activated precursors can be prepared using alcoholictetraethylammonium bicarbonate solutions (e.g., in nPrOH, iPrOH, nBuOH,better in EtOH or MeOH) for ¹⁸F⁻ elution. The eluate is concentratedunder reduced pressure. Precursor for radiolabelling in a suitablesolvent (e.g., tBuOH, tBuOH/MeCN, MeCN, etc.) is added and the reactionmixture is heated for a short time to give the respective active esterin more than 90% RCY. The building block is isolated via RP-SPE inexcellent radiochemical and chemical purity (Scheme 5C).

The present invention relates also to a kit comprising a containercontaining the compound of formula (II) and/or (III) as defined abovefor the preparation of PET contrast media. In certain embodiments, thekit provides packaged pharmaceutical compositions comprising apharmaceutically acceptable carrier and a compound of the invention. Incertain embodiments the packaged pharmaceutical composition willcomprise the reaction precursors necessary to generate the compound ofthe invention upon combination with a radiolabeled precursor. Otherpackaged pharmaceutical compositions provided by the present inventionfurther comprise indicia comprising at least one of: instructions forpreparing compounds according to the invention from supplied precursors,instructions for using the composition to image cells or tissuesexpressing PSMA, or instructions for using the composition to imageglutamatergic neurotransmission in a patient suffering from astress-related disorder, or instructions for using the composition toimage prostate cancer.

The present invention relates also to a device for the preparation ofthe active compounds referred to above, wherein the device comprisessuitable containers comprising any of the herein disclosed compounds,e.g. compounds according to formula (II) and/or (III). In oneembodiment, the device is suitable for synthesis of, e.g. [¹⁸F]DCFPyL1-10 starting from [¹⁸F]fluoride, preferably without HPLC purification.In one embodiment the device is an automated cassette module that issuitable for synthesis of, e.g. [¹⁸F]DCFPyL 1-10 starting from[¹⁸F]fluoride, preferably without HPLC purification, e.g. as shown inFIG. 4.

Application of the Radiolabelled Active Esters (III) for the Preparationof PET Tracers

An application of the ¹⁸F-labelled active esters synthesized accordingto the inventive procedures is exemplified by the simplified preparationof the PSMA-specific tracer [¹⁸F]DCFPyL 1-10.

According to the inventive method, [¹⁸F]F-Py-TFP 3c obtained under“nothing added conditions” was eluted from the resin with ethanol in asolution of HO-Lys-C(O)-Glu-OH 2b and tetraethylammonium bicarbonate inethanol (Scheme 6). The reaction mixture was heated at 40° C. for 3 min.[¹⁸F]DCFPyL 1-10 was isolated by RP-HPLC using 10% ethanol in isotonicsaline as an eluent to give after sterile filtration the ready to usesolution of the radiotracer.

In the inventive method ¹⁸F⁻ is trapped on an anion exchange resin andthen eluted directly with an alcoholic solution of the radiolabellingprecursor containing an onium group (X) like R² ₃N⁺, ArI⁺ or Ar₂S⁺. Thesolvent is removed under reduced pressure; the residue is taken up in asuitable solvent and heated for a short time. In case of highlyactivated radiolabelling precursors such as the precursor of[¹⁸F]F-Py-TFP 3c solvent removal is unnecessary. In this case analcoholic solution (except MeOH) of the onium [¹⁸F]fluoride salt issimply diluted with a suitable solvent and heated. Thepurification/isolation of the radiolabelled active esters isaccomplished by SPE or HPLC purification. Neither azeotropic drying nora base nor any other ingredients are needed. Alternatively, elution ofradiofluoride can be accomplished with tetraethylammonium bicarbonate(TEABC) in MeOH. In this case neither azeotropic drying nor any otheringredients are needed.

The inventive modifications of the common radiofluorination procedureallow a considerable shortening of the overall preparation time, due tothe reduction of a number of preparation steps. Additionallyradiofluorination according to Methods 1 and 2 is carried out under basefree conditions that enables one step preparation of the ¹⁸F-labelledactive esters even from less activated labelling precursors whereharsher reaction conditions (higher temperatures, longer reaction times)are necessary. These advantages allow to carry out the radiosynthesis inone pot making the inventive methods well-suited for automatedradiosyntheses, especially in microfluidic devices.

In contrast to the published radiosynthesis of [¹⁸F]DCFPyL 1-10 byPomper et al. the inventive method for the preparation of thisradiotracer allows to omit any evaporation steps, application ofwater-immiscible toxic and environmentally dangerous solvents (CH₂Cl₂),toxic reagents (TFA, anisole, MeCN), deprotection, HPLC purification andadditional formulation steps.

The inventive method enables automatic synthesis of [¹⁸F]DCFPyL 1-10 asshown in Example 3. Consequently, using the inventive method [¹⁸F]DCFPyL1-10 could be prepared faster and in higher isolated RCYs of up to 45%over 2 steps within only 55 min after end of bombardment (EOB) comparedto RCYs of 35% over 3 steps within 128 min EOB. The automatic synthesisyields [¹⁸F]DCFPyL 1-10 in isolated RCYs up to 35% in only 50 min.

Pharmaceutical Composition

Another aspect of the present invention relates to pharmaceuticalcompositions comprising at least one compound of formula (I) togetherwith at least one pharmaceutically acceptable solvent, ingredient and/ordiluents. Said pharmaceutical composition is useful for imaging prostatecancer cells or prostate cancerous tissue. Pharaceutically acceptableingredient refers to especially antiviral, antibacterial or antifungalagents. Diluent includes any one of sterile saline, sodium chlorideinjection, Ringer's injection, dextrose injection, dextrose and sodiumchloride injection, lactated Ringer's injection and other aqueous buffersolution. The amount of diluent in the composition can range from about5 to about 95% by weight of the total composition, preferably from about25 to about 75 weight %, and more preferably from about 30 to about 60weight %. The inventive pharmaceutical composition may be administeredby injection (intravenous, intraperitoneal, intramuscular,subcutaneous).

PET Imaging

So far the only PSMA PET tracer used in clinics is [⁶⁸Ga]HBED-CC (50).⁶⁸Ga has a half-life of 68 min and is obtained from a generator systemin only moderate amounts that precludes the broad application of[⁶⁸Ga]HBED-CC (50) in clinical practice. In contrast, ¹⁸F has theadvantage of a longer half-life (110 min) and is accessible in highamounts of up to 74 GBq or more. This permits the centralized productionand regional distribution as practiced in the supply of [¹⁸F]FDG forclinical use. In a suitable PSMA⁺ PCa mice model [¹⁸F]DCFPyL 1-10displays imaging characteristics nearly identical to those of[⁶⁸Ga]HBED-CC (50). Moreover, kidney uptake of [¹⁸F]DCFPyL 1-10 is muchlower as that of [⁶⁸Ga]HBED-CC (50). This should improve the detectionof tumor lesions in the abdomen. Therefore, taking into an easyaccessibility of [¹⁸F]DCFPyL 1-10 according to the present invention itcould represents an adequate alternative for [⁶⁸Ga]HBED-CC (50) forresearch and patient care.

DESCRIPTION OF FIGURES

FIG. 1: Automatic synthesis of [¹⁸F]DCFPyL with HPLC purification in aTRACERLab FX_(fn) automated radiochemistry synthesis module (GE MedicalSystems).

FIG. 2: [⁶⁸Ga]HBED-CC- (50) versus [¹⁸F]DCFPyL (1-10)-PET in PSMA⁺ PCabearing mice. Shown are measurements in the same animal, on twoconsecutive days. Cursor position is indicated by crosslines.Abbreviations: K: kidney; T: tumor. Scale bar: 10 mm.

FIG. 3: Automatic synthesis of [¹⁸F]DCFPyL without HPLC purification ina TRACERLab FX_(fn) automated radiochemistry synthesis module (GEMedical Systems). Reference signs A to I in FIG. 3 have the followingmeaning:

A 3 mL EtOH (absolute) B 200 μL [¹⁸F]F—Py-TFP-precursor solution C 2 mLtBuOH/MeCN (4:1) D 10 mL H₂Or E 15 mL H₂O F 500 μL [¹⁸F]DCFPyL-precursorsolution G 3 mL H₂O H 10 mL H₂O I 60 mL 1.7% H₃PO₄ J 9 mL Isotonic NaClK 2 mL Isotonic NaCl with 50 Vol % EtOH L 10 mL H₂O M 20 mL 0.1% TFA

FIG. 4: Automated cassette module synthesis of [¹⁸F]DCFPyL 1-10 startingfrom [¹⁸F]fluoride without HPLC purification

EXAMPLES

Abbreviations:

βAla (beta-alanine), Boc (tert-butyloxycarbonyl), DCC(N,N′-dicyclohexylcarbodiimide), DMF (dimethylformamide), DMM(dimethoxymethane), DMSO (dimethyl sulfoxide), EDC(1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), EDTA(ethylenediaminetetraacetic acid), Glu (glutanic acid), Gly (glycine),Lys or syL (lysine) mCPBA (meta-chloroperoxy benzoic acid), MeCN(acetonitrile), ONSu (N-oxy-succinimide), OTf(trifluoromethanesulfonate), Tos (tosyl), PMB (p-methoxybenzyl), Py(pyridinyl), tBu (tert-butyl), TFA (trifluoroacetic acid), TFE(tetrafluoroethyl alcohol), TFP (2,3,5,6-tetrafluorophenyl), THF(tetrahydrofuran), TIS (triisopropylsilane), TMS (trimethylsilyl).

Example 01: Preparation of2,3,5,6-Tetrafluorophenyl-6-[¹⁸F]fluoronicotinate ([¹⁸F]F-Py-Tfp, 3c)

Procedure A:

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was trapped on a anion-exchangeresin (QMA or Chromafix® 30-PS—HCO₃ cartridge). It should be noted, thatin the case of QMA cartridges, the aqueous [¹⁸F]fluoride was loaded ontothe cartridge from the male side, whereas EtOH flushing and ¹⁸F⁻ elutionwere done from the female side of the cartridge. The cartridge waswashed with EtOH (1 mL) and [¹⁸F]fluoride was eluted from the resin intothe reaction vial withN,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate 4c (10 mg, 20 μmoL) in EtOH (200 μL) followedby MeCN/tBuOH 1:4 (2 mL). The mixture was stirred for 15 min at 40° C.After cooling to ambient temperature, the reaction mixture was dilutedwith water (20 mL) and loaded onto a polymer RP cartridge (the cartridgewas preconditioned with 2 mL EtOH followed by 30 mL H₂O). The cartridgewas washed H₂O (5 mL) and [¹⁸F]F-Py-Tfp 3c (up to 15 GBq, 70-75% EOB;not decay corrected) was eluted with EtOH (300 μL). The radiochemicaland chemical purities after SPE purification were >98% determined byanalytical HPLC (Eluent: Water with 50% MeCN. Flow rate: 1.5 mL/min.Column: Chromolith® SpeedROD RP-18e column (Merck, Darmstadt Germany),50×4.6 mm. Retention time: [¹⁸F]F-Py-Tfp 3c˜2 min).

Procedure B:

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was trapped on a anion-exchangeresin (QMA or Chromafix® 30-PS—HCO₃ cartridge). It should be noted, thatin the case of QMA cartridges, the aqueous [¹⁸F]fluoride was loaded ontothe cartridge from the male side, whereas EtOH flushing and ¹⁸F⁻ elutionwere done from the female side of the cartridge. [¹⁸F]fluoride waseluted from the resin into the reaction vial with methanolictetraethylammonium bicarbonate solution (5 mg, 500 μL). The solvent wasremoved under reduced pressure at 70 C within 2 min. Afterwardsprecursor dissolved in MeCN/tBuOH 1:4 (2 mL) was added and the mixturewas stirred for 15 min at 40° C. After cooling to ambient temperature,the reaction mixture was diluted with water (20 mL) and loaded onto apolymer RP cartridge (the cartridge was preconditioned with 2 mL EtOHfollowed by 30 mL H₂O). The cartridge was washed H₂O (5 mL) and[¹⁸F]F-Py-Tfp 3c (up to 15 GBq, 70-75% EOB; not decay corrected) waseluted with EtOH (300 μL). The radiochemical and chemical purities afterSPE purification were >98% determined by analytical HPLC (Eluent: Waterwith 50% MeCN. Flow rate: 1.5 mL/min. Column: Chromolith® SpeedRODRP-18e column (Merck, Darmstadt Germany), 50×4.6 mm. Retention time:[¹⁸F]F-Py-Tfp 3c˜2 min).

Example 02: Preparation of [¹⁸F]DCFPyL 1-10

To a freshly prepared ethanolic solution of HO-Lys-C(O)-Glu-OH 2b (2.5mg, 100 μL) and tetraethylammonium bicarbonate (0.5 M) in EtOH (60 μL)an ethanolic solution of [¹⁸F]F-Py-Tfp 3c (0.05-10 GBq in 150 μL) wasadded. The reaction mixture was stirred for 3 min at 40° C. Afterwardsthe mixture was quenched with water (2 mL) and purified by preparativeHPLC. Eluent: saline (0.9% NaCl) with 10% EtOH. Flow rate: 8 mL/min.Column: Synergi 4 μm Hydro-RP 80 Å 100×21.2 mm. Retention time: ˜7 min.The purified product was sterile filtered before use. [¹⁸F]DCFPyL 1-10was obtained in 75-90% RCY (decay-corrected). The radiochemical andchemical purities after HPLC purification were >98%, determined byanalytical HPLC: Eluent: phosphoric acid buffer solution (pH=2) with 10%EtOH for 5 min, then 50% for 2 min. Flow rate: 1.5 mL/min. Column:Chromolith® SpeedROD RP-18e column (Merck, Darmstadt Germany), 50×4.6mm. Retention times: [¹⁸F]DCFPyL˜3 min; [¹⁸F]F-Py-Tfp˜5.7 min).

Example 03: Automated Synthesis of [¹⁸F]DCFPyL 1-10 Starting from[¹⁸F]Fluoride Using Final HPLC Purification (FIG. 1)

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was vacuum-transferred from thetarget to a trapping vial. Aqueous [¹⁸F]fluoride was then transferredfrom the trapping vial through an anion-exchange resin cartridge (QMA)from the male side of the cartridge, and [¹⁸O]H₂O was collected in aseparate vial. The cartridge was subsequently washed with EtOH (1 mL)from vial A from the female side of the cartridge. Washings werediscarded. Thereafter, [¹⁸F]fluoride was eluted from the resin withN,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate 4c (10 mg, 20 μmoL) in EtOH (200 μL) from vialB into reactor R1. After this, MeCN/tBuOH 1:4 (2 mL) from vessel C waspassed through the cartridge into reactor R1. Reactor R1 was filled withhelium, sealed and the reaction mixture was heated at 45° C. for 20 min.After cooling to room temperature the crude [¹⁸F]F-Py-Tfp 3c wastransferred into the collecting vial C1, containing 20 mL H₂O. Thesolution was passed through a polymer RP cartridge (Strata X). Thecartridge was washed with H₂O (5 mL) from reservoir D and dried byapplying a helium stream for 5 min. [¹⁸F]F-Py-Tfp 3c was eluted withEtOH (400 μL) from vial E into reactor R2 containing a mixture of afreshly prepared ethanolic solution of HO-syL-C(O)-Glu-OH 2b (2.5 mg,100 μL) and 0.5 M tetraethylammonium bicarbonate in EtOH (60 μL). Afteraddition of [¹⁸F]F-Py-Tfp, the reaction mixture was heated at 40° C. for3 min. After cooling to room temperature the reaction mixture wasdiluted with H₂O (2 mL) from vial F and [¹⁸F]DCFPyL was loaded onto theHPLC for purification. The crude tracer was purified by preparative HPLCto give [¹⁸F]DCFPyL 1-10 in 40-65% RCY (from ¹⁸F⁻; decay-corrected) in≥95% radiochemical purity. Eluent: saline (0.9% NaCl) with 10% EtOH.Flow rate: 8 mL/min. Column: Synergi 4 am Hydro-RP 80 Å 100×21.2 mm.Retention time: ˜7 min. The purified product was sterile filtered beforeuse as (determined by analytical HPLC (Quality control): Eluent:phosphoric acid buffer solution (pH=2) with 10% EtOH for 5 min, thenphosphoric acid buffer solution (pH=2) with 50% EtOH for 2 min. Flowrate: 1.5 mL/min. Column: Chromolith® SpeedROD RP-18e column (Merck,Darmstadt Germany), 50×4.6 mm. Retention times: [¹⁸F]DCFPyL˜3 min;[¹⁸F]F-Py-Tfp˜5.7 min).

Example 04: Preparation of 2,3,5,6-Tetrafluorophenyl 4-Iodobenzoate 20

Et₃N (1.504 mL, 0.76 g, 7.51 mmol) was added dropwise to a vigorouslystirred solution of 4-iodobenzoyl chloride 19 (2 g, 7.51 mmol) and2,3,5,6-tetrafluorophenol (1.25 g, 7.51 mmol) in Et₂O (60 mL) and thestirring was continued for a further 10 min. The reaction mixture wasfiltered, the filter cake was washed with Et₂O (30 mL) and the filtratewas concentrated under reduced pressure. The residue was dissolved Et₂O(10 mL) and filtered. The filtrate was concentrated under reducedpressure. The residue was recrystallized from Et₂O/hexane to give thetitle compound (1.38 g, 48%) as a colorless solid.

R_(f)=0.46, EtOAc:hexane=1:10.

¹H-NMR (CDCl₃, 300 MHz): δ=7.07 (tt, J=9.9, 7.1 Hz, 1H), 7.82-7.98 (m,4H);

¹⁹F-NMR (CDCl₃, 282.4 MHz): δ=−152.70, −138.80;

¹³C-NMR (CDCl₃, 75.5 MHz): δ=103.0, 103.4 (t, J=23.0 Hz), 126.6, 131.9,138.3, 138.9-142.7 (m), 144.4 (dt, J=3.8, 12.1 Hz), 147.7 (dt, J=4.5,12.1 Hz), 162.2. MS (ESI): positive mode m/z=397.3 ([M+H]⁺). MS (EI, 70eV): m/z (%): 395.9 [M⁺] (3), 230.9 [C₇H₄OI⁺] (100), 202.9 [C₆H₃I⁺](100), 104.0 [C₇H₄O] (10).

Example 05: Preparation of (4-Methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodonium tosylate 21

Tos.H₂O (0.72 g, 3.79 mmol) was added to a solution of2,3,5,6-tetraphenyl 4-iodobenzoate 20 (1 g, 2.52 mmol), mCPBA [1.44 g,85% purity, 7.09 mmol; commercially available 77% mCPBA (Aldrich) wasdried at 2 mbar and 40° C. for 3 h before use] and anisole (0.51 mL,0.51 g, 4.72 mmol) in 50% CF₃CH₂OH (TFE) in CH₂Cl₂ (20 mL) and themixture was stirred for 3 days. The reaction mixture was added tovigorously stirred Et₂O (450 mL) and stirring was continued for afurther 45 min. The precipitate was filtered off and washed with Et₂O(100 mL), redissolved in CH₂Cl₂ (20 mL) and filtered through Celite®.The filtrate was concentrated under reduced pressure. The residue wasrecrystallized from CH₂Cl₂/Et₂O to give the title compound (1.53 g, 90%)as a colorless solid.

¹H-NMR (CDCl₃, 300 MHz): δ=2.28 (s, 3H), 3.77 (s, 3H), 6.80 (d, J=9.0Hz, 2H), 6.97 (d, J=6.0 Hz, 2H), 7.01-7.14 (m, 1H), 7.36 (d, J=9.0 Hz,2H), 7.98-8.03 (m, 4H), 8.18 (d, J=9.0 Hz, 2H);

¹⁹F-NMR (CDCl₃, 282.4 MHz): δ=−152.70, −138.55;

¹³C-NMR (CDCl₃, 75.5 MHz): δ=21.2, 55.5, 103.7 (t, J=23.0 Hz), 104.7,117.4, 123.0, 125.9, 128.5, 129.3, 132.7, 135.3, 137.9, 138.8-423142.3(m), 139.6, 142.2, 144.4 (dt, J=3.8, 15.9 Hz), 147.7 (dt, J=4.5, 16.6Hz), 161.3, 162.4.

MS (ESI): positive mode m/z=503.0 ([M]+); MS (ESI): negative modem/z=171.0 ([C₇H₇SO₃]⁻); ESI HRMS: calcd for C₂₀H₁₂F₄O₃I⁺: 502.9762;found: 502.9769.

Example 06: Preparation of (4-Methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodonium iodide 22

(4-Methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodoniumtosylate 21 (1.19 g, 1.76 mmol) was dissolved in CH₂Cl₂ (20 mL). Afteraddition of saturated NaI (10 mL), the mixture was vigorously stirredfor 15 min and centrifuged (4000 rpm, 15° C., 10 min). The aqueoussolution and precipitate were separated off, saturated NaI (10 mL) wasadded and the mixture was vigorously stirred for 15 min and centrifuged(×3). The organic fraction was filtered, dried and concentrated underreduced pressure. The residue was recrystallized from CH₂Cl₂/Et₂O, theprecipitate was filtered off, washed with acetone (10 mL) and Et₂O (80mL) to give the title compound (0.29 g, 26%) as an off-white solid. Thesubstance could be stored at 4° C. under argon at least for 4 months.However, it was unstable in solution especially at elevated temperatures(dissolved in DMF or DMSO it was unstable already at ambienttemperature).

¹H-NMR (CDCl₃, 300 MHz): δ=3.79 (s, 3H), 6.65-6.73 (m, 2H), 6.95-7.10(m, 1H), 7.56 (d, J=8.9 Hz, 2H), 7.81-8.05 (m, 3H), 8.21-8.35 (m, 1H);

¹⁹F-NMR (CDCl₃, 282.4 MHz): δ=−152.63, −138.72;

¹³C-NMR (CDCl₃, 75.5 MHz): δ=55.5, 82.3, 103.0, 103.5 (t, J=22.6 Hz),116.4, 126.6, 128.8, 131.9, 138.3, 138.6-142.5 (m), 144.2-144.7 (m),144.5-144.9 (m), 159.5, 162.2.

MS (ESI): positive mode m/z=502.9 ([M]+); MS (ESI): negative modem/z=126.9 ([I]⁻);

ESI HRMS: calcd for C₂₀H₁₂F₄O₃+: 502.9762; found: 502.9741.

Example 07: Preparation of (4-Methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodonium perchlorate 4a

To a solution of(4-methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]-iodoniumiodide 22 (0.2 g, 0.32 mmol) in acetone (12 mL) and AgClO₄ (66 mg, 0.32mmol) was added. The reaction mixture was shaken for 1 min, precipitatedAgI was separated by centrifugation. The supernatant was concentratedunder reduced pressure and the residue was recrystallized fromCH₂Cl₂/Et₂O to give the title compound (168 mg, 88%) as a colorlesssolid.

¹H-NMR (CDCl₃, 300 MHz): δ=3.80 (s, 3H), 6.88-6.98 (m, 2H), 7.06 (tt,J=9.9, 7.1 Hz, 1H), 8.04-8.13 (m, 2H), 8.14-8.18 (m, 2H), 8.21-8.26 (m,2H);

¹⁹F-NMR (CDCl₃, 282.4 MHz): δ=−152.52, −138.48;

¹³C-NMR (CDCl₃, 75.5 MHz): δ=55.5, 101.1, 103.8 (t, J=21.1 Hz), 118.4,120.1, 130.6, 133.5, 135.1, 138.3, 138.7-139.3 (m), 142.1-144.4 (m),147.5-147.7 (m), 161.0, 163.4.

MS (ESI): positive mode m/z=503.0 ([M]⁺); ESI HRMS: calcd forC₂₀H₁₂F₄O₃I⁺: 502.9762; found: 502.9769. MS (ESI): positive modem/z=503.0 ([M]⁺); MS (ESI): negative mode m/z=171.0 ([C₇H₇SO₃]⁻); ESIHRMS: calcd for C₂₀H₁₂F₄O₃I⁺: 502.9762; found: 502.9749.

Example 08: Preparation of 2,3,5,6-tetrafluorophenyl 4-fluorobenzoate 24

Et₃N (0.54 mL, 0.39 g, 3.87 mmol) was added dropwise to a vigorouslystirred solution of 4-fluorobenzoyl chloride 25 (0.46 mL, 0.61 g, 3.87mmol) and 2,3,5,6-tetrafluorophenol (0.64 g, 3.87 mmol) in Et₂O (30 mL)and the stirring was continued for a further 10 min. The reactionmixture was filtered, washed with H₂O (15 mL) and brine (2×10 mL), driedand concentrated under reduced pressure. The residue was recrystallizedfrom hexane to give 24 (0.41 g) as a colorless solid. The mother liquorwas concentrated under reduced pressure and the residue wasrecrystallized from hexane to give a second crop of 24 (0.45 g, total77%).

R_(f)=0.62, EtOAc:hexane=1:10.

¹H-NMR (CDCl₃, 300 MHz): δ=7.07 (tt, J=9.9, 7.1 Hz, 1H), 7.21-7.30 (m,2H), 8.21-8.37 (m, 2H);

¹⁹F-NMR(CDCl₃, 282.4 MHz): δ=−152.75, −138.93, −102.24;

¹³C-NMR (CDCl₃, 75.5 MHz): δ=103.4 (t, J=21.9 Hz), 116.2 (d, J=21.9 Hz),123.5 (d, J=1.5 Hz), 133.5 (d, J=2.3 Hz), 139.0-142.7 (m), 144.5-145.1(m), 147.3-148.2 (m), 163.3 (d, J=259.7 Hz), 168.5. MS (ESI): positivemode m/z=288.3 ([M]+). MS (EI, 70 eV): m/z (%): 165.0 [C₆HF₄O⁺] (10),123.0 [C₆H₄FO⁺] (100), 95.0 [C₆H₄F⁺] (10).

Example 09: Preparation of 2,3,5,6-tetrafluorophenyl4-[¹⁸F]fluorobenzoate 3a

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was trapped on a anion-exchangeresin (QMA or Chromafix® 30-PS—HCO₃ cartridge). It should be noted, thatin the case of QMA cartridges, the aqueous [¹⁸F]fluoride was loaded ontothe cartridge from the male side, whereas MeOH flushing and ¹⁸F-elutionwas done from the female side of the cartridge. If the QMA cartridge hasbeen loaded, flushed and eluted from the female side only, sometimes asignificant amount of [¹⁸F]fluoride remained on the resin (this isprobably because QMA-light (46 mg) cartridges have a single frit on themale side but four on the female side). The cartridge was washed withMeOH (1 mL) and [¹⁸F]fluoride was eluted into a reaction vial with asolution of (4-methoxyphenyl)[4-(2,3,5,6-tetrafluorophenoxycarbonyl)phenyl]iodonium perchlorate (5mg) 4a in MeOH (0.5 mL). Methanol was evaporated under reduced pressureat 70° C. within 2-3 min. After cooling to room temperature DMSO (500VL) was added. The reaction mixture was stirred at 130° C. for 10 min.Subsequently the mixture was cooled down to room temperature, water (4mL) was added and the reaction mixture was shaken vigorously for 30 s.Analysis of the mixture by radio-HPLC showed formation of the desired¹⁸F-labelled active ester in 24% RCY. HPLC conditions: column:Chromolith® SpeedROD RP-18e (Merck, Darmstadt Germany), 50×4.6 mm;eluent: 50% MeCN; flow rate: 3 mL/min.

Example 10: Preparation of 2,3,5,6-tetrafluorophenyl6-[¹⁸F]fluoropyridazine-3-carboxylate (3e)

3e can be prepared from radiolabelled precursor 4e using one of twoalternative radiolabelling procedures. According to the first one ¹⁸F⁻is fixed on an anion exchange resin. The resin is washed with EtOH anddrained. ¹⁸F is eluted with an ethanolic solution of 4e. The resin isadditionally washed with tBuOH/MeCN 1:4 and the collected eluates areheated for a short time. Finally 3e is isolated via SPE. Alternatively3e is eluted with methanolic tetraethylammonium bicarbonate, the solventis evaporated and the residue is taken up in a solution of 4e intBuOH/MeCN 1:4 and heated for a short time. Finally the desired activeester is isolated via SPE. Radiolabelling precursor 4e can be preparedfrom commercially available precursor 14 as follows: Esterification with1,2,5,6-tetrafluorophenol/DCC, treatment of the intermediate activeester 15 with anhydrous trimethylamine in THF followed by anionmetathesis using TMSOTf. The reference compound 18 can be prepared fromintermediate 15 by treatment with AgF under anhydrous conditions.

Example 11: Preparation 2,3,5,6-tetrafluorophenyl5-[¹⁸F]fluoropyrazine-2-carboxylate (3f)

Compound 3f can be prepared exactly as 3e as described in the Example10.

Example 12: Preparation of 2,3,5,6-tetrafluorophenyl4-[¹⁸F]fluoro-2,3,5,6-tetrafluorobenzoate (3d)

Compound 3d can be prepared exactly as 3e as described in the Example10.

Example 13: Preparation of(2S)-2-({[(1S)-1-carboxy-5-{[6-[¹⁸F]fluoropyridazin-3-yl]formamido}pentyl]carbamoyl}amino)butanedioicacid (1-17)

Compound 1-17 can be prepared exactly as [¹⁸F]DCFPyL (1-10) as describedin the Example 2.

Example 14: Preparation of(2S)-2-({[(1S)-1-carboxy-5-{[5-[¹⁸F]fluoropyrazin-2-yl]formamido}pentyl]carbamoyl}amino)butanedioicacid (1-29)

Compound 1-29 can be prepared exactly as [¹⁸F]DCFPyL ([¹⁸F] 1-10) asdescribed in the Example 2.

Example 15: Preparation of(2S)-2-({[(1S)-1-carboxy-5-(3-{[6-[¹⁸F]fluoropyridin-3-yl]formamido}propanamido)pentyl]carbamoyl}amino)butanedioicacid (1-31)

Compound 1-33 can be prepared analogously to [¹⁸F]DCFPyL ([¹⁸F]1-10)using 2d instead of 2b. 2d can in turn be prepared using conventionalmethods of peptide synthesis, for example, via acylation of known 37with Boc-βAla-ONSu followed by cleavage of protecting groups.

Example 16: Preparation of (2S)-2-({[(1S)-1-carboxy-5-(2-{[6-[¹⁸F]fluoropyridazin-3-yl]formamido}acetamido)pentyl]carbamoyl}amino)butanedioicacid (1-32)

Compound 1-32 can be prepared analogously to [¹⁸F]DCFPyL (1-10) using 2pinstead of 2b. 2p can in turn be prepared using conventional methods ofpeptide synthesis, for example, via acylation of known 37 withBoc-Gly-Gly-ONSu followed by cleavage of protecting groups.

Example 17: Preparation of(2S)-2-({[(1S)-1-carboxy-5-[(4S)-4-carboxy-4-{[4-[¹⁸F]fluoro-2,3,5,6-tetrafluorophenyl]formamido}butanamido]pentyl]carbamoyl}amino)butanedioicacid (1-33)

Compound 1-33 can be prepared analogously to [¹⁸F]DCFPyL (1-10) using 2kinstead of 2b. 1-33 can in turn be prepared using conventional methodsof peptide synthesis, for example, via acylation of known 37 withBoc-Glu(ONSu)-OtBu followed by cleavage of protecting groups.

Example 18: Preparation of(2S)-2-({[(1S)-1-carboxy-5-[(4S)-4-carboxy-4-[(4S)-4-carboxy-4-{[6-[¹⁸F]fluoropyridin-3-yl]formamido}butanamido]butanamido]-pentyl]carbamoyl}amino)butanedioicacid (1-34)

Compound 1-34 can be prepared analogously to [¹⁸F]DCFPyL ([¹⁸F]1-10)using 2n instead of 2b. 2n can in turn be prepared using conventionalmethods of peptide synthesis, for example, via acylation of known 37with Z-Glu(ONSu)-OtBu followed by cleavage of Z (Z=benzyloxycarbonyl,Boc=tert-butyloxycarbonyl) group, followed by acylation of intermediate49 with Boc-Glu(ONSu)-OtBu and final deprotection with TFA.

Example 19: Comparison of [¹⁸F]DCFPyL ([¹⁸F]1-10) with [⁶⁸Ga]HBED-CC(50) in PSMA⁺-PCa Xenograft Mice

Methods:

Five 8-week-old male C.B-Igh-1b/IcrTac-Prkdcscid mice (Taconic) wereinjected subcutaneously in the neck region with 4×10⁶ LNCaP-C4-2prostate tumor cells. Three weeks after tumor implantation, two PETmeasurements with [¹⁸F]DCFPyL ([¹⁸F]1-10) and [⁶⁸Ga]HBED-CC (50),respectively, were performed using an Inveon μPET/CT scanner (Siemens)with a resolution of 1.4 mm FWHM at center of field of view. The firstPET measurement was immediately followed by a CT scan during which theanimal was left in the same position. Both tracers were injected i.v.through the lateral tail vein ([¹⁸F]1-10: 21-32 MBq; [⁶⁸Ga]HBED-CC:19-33 MBq, on two consecutive days). Emission data collection started 60min after injection and lasted 45 min. Image reconstruction wasperformed using Fourier rebinning and an ordered subset expectationmaximization (3D-OSEM) procedure, yielding images with voxel sizes of0.78×0.78×0.80 mm. Image analysis was performed with VINCI 4.0 (MPI forMetabolism Research, Cologne, Germany). Tracer uptake in the tumor aswell as liver, kidney, and background was determined using volumes ofinterest (VOIs) covering the respective structure. Significantdifferences were assessed using two-way repeated measures ANOVA withfactors “structure” and “tracer”, followed by Holm-Sidak post hoccomparison. Tumor sizes were measured by drawing accurate tumor VOIs inthe CT images, and extracting VOI volume. Tracer uptake was correlatedtumor size using the Pearson correlation test.

Results

As shown in FIG. 2, tumor tracer uptake was similar for the two tracers(FIG. 2): 1.4±1.7% ID/g for [¹⁸F]1-10, and 1.8±2.0% ID/g for[⁶⁸Ga]HBED-CC (50) (not significant). There was a significant positivecorrelation between tumor size and tracer uptake for both tracers:R=0.97, p=0.0059 for [¹⁸F]1-10, and R=0.98, p=0.0019 for [⁶⁸Ga]HBED-CC(50). Signal-to-noise ratio (tumor versus background) was nearlyidentical as well with 5.9±4.2 for [¹⁸F]1-10, and 6.7±6.9 for[⁶⁸Ga]HBED-CC (50). While liver uptake was similar as well (1.1±0.5%ID/g for [¹⁸F]1-10, and 0.7±0.2% ID/g for [⁶⁸Ga]HBED-CC (50); notsignificant), [¹⁸F]1-10 uptake in the kidney (3.0±1.9% ID/g) wassignificantly lower than [⁶⁸Ga]HBED-CC (50) uptake (13.9±6.4% ID/g;F(3,12)=25.6, p<0.0001 for factor interaction, post-hoc p<0.05).

Example 20: Automated Synthesis of [¹⁸F]DCFPvL 1-10 Starting from[¹⁸F]Fluoride without HPLC Purification (FIG. 3)

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was transferred from the target to atrapping vial. Aqueous [¹⁸F]fluoride was then vacuum-transferred fromthe trapping vial through an anion-exchange resin cartridge (Sep-Pak QMAcarbonate light 46 mg, preconditioned with 1 mL water) from the maleside of the cartridge, and [¹⁸O]H₂O was collected in a separate vial.The cartridge was subsequently washed with EtOH (3 mL) from vial A fromthe female side of the cartridge. Washings were discarded. Thereafter,[¹⁸F]fluoride was slowly eluted from the resin withN,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate 4c (10 mg, 20 μmoL) in EtOH (200 μL) from thevial B into reactor R1 with a low flow of helium. After this, MeCN/tBuOH1:4 (2 mL) from vessel C was passed through the cartridge into reactorR1. Reactor R1 was filled with helium, sealed and the reaction mixturewas heated at 45° C. for 15 min. After cooling to room temperature thecrude [¹⁸F]F-Py-Tfp 3c was diluted with water (15 mL) from vessel E andpassed through a polymer RP cartridge (Strata X, preconditioned with 1mL EtOH and washed with 5 mL water). The cartridge was washed with H₂O(10 mL) from reservoir D and dried by applying a helium stream for 5min. [¹⁸F]F-Py-Tfp 3c was eluted with a mixture of ethanol (250 μL),freshly prepared ethanolic solution of HO-syL-C(O)-Glu-OH 2b (2.5 mg,100 μL) and 0.5 M tetraethylammonium bicarbonate in EtOH (60 μL) fromvial F into reactor R2. The reaction mixture was heated at 40° C. for 3min. After cooling to room temperature the reaction mixture was dilutedwith water from vial G and transferred to vessel M containing 0.1% TFA(20 mL). The acidic solution was loaded onto a tC18 cartridge (Sep-PaktC18 Plus Long Cartridge, 900 mg, preconditioned with 10 mL EtOH andwashed with 30 mL water). The cartridge was subsequently washed withwater (10 mL) from vial H and [¹⁸F]DCFPyL was eluted with 10%EtOH-solution of 1.7% phosphoric acid (60 mL) onto a HLB catridge (OasisHLB Plus Short Cartridge 225 mg, preconditioned with 10 mL EtOH andwashed with 30 mL water) from Vessel I. The HLB cartridge was washedwith 10 mL water by vessel L and [¹⁸F]DCFPyL was eluted with 50 Vol %ethanol in isotonic saline (2 mL; v/v). The solution was diluted withisotonic saline (9 mL) and sterile filtered. Quality control: eluent:phosphoric acid (1.7%) with 10% EtOH for 5 min, then with 50% EtOH for 2min. Flow rate: 3 mL/min. Column: Chromolith® SpeedROD RP-18e column(Merck, Darmstadt Germany), 50×4.6 mm. Retention times: [¹⁸F]DCFPyL˜3min; [¹⁸F]F-Py-Tfp˜5.7 min.

Example 21: Automated Cassette Module Synthesis of [¹⁸F]DCFPyL 1-10Starting from [¹⁸F]Fluoride without HPLC Purification (FIG. 4)

Aqueous [¹⁸F]fluoride (0.05-50 GBq) was transferred from the target tothe receiver vial at position E. Aqueous [¹⁸F]fluoride was then vacuumtransferred from the receiver vial E through an anion-exchange resincartridge (Sep-Pak QMA carbonate light 46 mg, preconditioned with 1 mLwater) via CP

Ba

A. [¹⁸O]H₂O was collected in the collection vial. The cartridge wassubsequently washed with EtOH (1 mL) from reservoir D by action ofsyringe 1 (S1) via D

S1 and then S1

B

C

Waste two times. Thereafter, [¹⁸F]fluoride was slowly eluted from theresin withN,N,N-trimethyl-5-[(2,3,5,6-tetrafluorophenoxy)-carbonyl]pyridine-2-aminiumtrifluoromethanesulfonate 4c (10 mg, 20 μmoL) in EtOH (200 μL) from thevial at position J into the reactor via J

S1 and then S1

B

C

G. The reaction solvent MeCN/tBuOH 1:4 (2 mL) from vessel at position Kwas passed through the cartridge into the reactor via K

S1 and then S1

B

C

G, too. The reactor was sealed and the reaction mixture was heated at50° C. for 15 min. The crude [¹⁸F]F-Py-Tfp 3c was purified by SPE. Thiswas accomplished by a stepwise dilution procedure of the crude reactionmixture. At first the hot reaction mixture was quenched with water (2ml) from the reservoir at position M by action of syringe 2 (S2) via M

S2 and then S2

G. Then syringe 2 was partially filled with water (5.5 mL) via M

S2, and an aliquot (1 mL) crude [¹⁸F]F-Py-Tfp was sucked into thesyringe 2 via G

S2. The diluted solution was passed through a small C18 cartridge(Sep-Pak C18 Plus Light Cartridge, 130 mg) at position H via S2

H

R

Waste. The whole procedure was repeated until full recovery of thereaction mixture was achieved. The cartridge was washed with water (5mL) via M

S2 and S2

H

R

Waste, and dried with a nitrogen stream for 20 s via A

H

R

Waste. The reactor, manifold, the tubing H

R and syringe 1 was thoroughly cleaned by a procedure involving flushingwith ethanol and dried with a stream of nitrogen. The [¹⁸F]F-Py-Tfp 3cwas eluted from the small C₁₈ cartridge with a solution ofHO-syL-C(O)-Glu-OH 2b (2.5 mg) and 0.5 M tetraethylammonium bicarbonatein EtOH (500 VL) from vial at position L into reactor via L

R

H

G by applying vacuum at V

Reactor. The reaction mixture was heated at 40° C. for 3 min and,thereafter, quenched with 0.5% trifluoroacetic acid (4 mL) from vesselat position N via N

S2 and S2

G. The acidic solution of [¹⁸F]DCFPyL was further diluted with H₂O andloaded onto a tC18 cartridge (Sep-Pak tC18 Plus Long Cartridge, 900 mg,preconditioned with 5 mL EtOH and washed with 15 mL water). To achievethis, syringe 2 was partially filled with water (4 mL) via M

S2, then an aliquot of the crude reaction mixture (1 mL) was sucked intothe syringe 2 via G

S2. This solution was passed through the tC18 cartridge (Sep-Pak C18Plus Light Cartridge, 130 mg) via S2

H

R

Waste. The whole dilution procedure was performed at least four times toarchive full recovery of the reaction mixture in the reactor. Thecartridge was subsequently washed with water (5 mL) from the reservoirvia M

S2 and S2

H

R

Waste, and dried by applying a high flow nitrogen stream for 5 s via A

H

R

Waste. The [¹⁸F]DCFPyL was stepwise eluted from the tC₁₈ phase with 10Vol % EtOH-solution of 1.7% phosphoric acid (total volume of 60 mL) ontoa HLB cartridge (Oasis HLB Plus Short Cartridge 225 mg, preconditionedwith 5 mL EtOH and washed with 15 mL water) from vessel at position O byaction of syringe 2 via O

S2 and then S2

P

Q

S

T

Waste to archive further purification. After this, the HLB cartridge waswashed with 10 mL water via M

S2 and then S2

S

T

Waste. The purified [¹⁸F]DCFPyL was eluted with ethanol (1 mL) fromreservoir D via D

S1 into syringe 3 (S3) via S1

S

T

S3. The ethanolic [¹⁸F]DCFPyL solution in syringe 3 was further dilutedwith isotonic saline (total volume of 10 mL) from vessel I via I

S

T

S3 and dispensed upon operators request into the tracer vial at positionU (S3

U) with simultaneous sterile filtration to give the PET-tracer as aready for injection solution in 9% EtOH in isotonic saline. Qualitycontrol: eluent: 1.7% phoshoric acid/EtOH=9/1 for 5 min, then 1.7%phoshoric acid/EtOH=1/1 for 2 min. Flow rate: 3 mL/min. Column:Chromolith® SpeedROD RP-18e column (Merck, Darmstadt Germany), 50×4.6mm. Retention times: [¹⁸F]DCFPyL˜3 min; [¹⁸F]F-Py-Tfp˜5.7 min.

Additional Embodiments of the Invention

-   1. A method for preparing a compound of formula (I)

-   -   wherein    -   A, B, C, and D represent independently of each other C—H, C—F or        N; and not more than two of A, B, C, and D represent N;    -   E represents a covalent bond or

-   -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃        haloalkoxy, C₂-C₄ alkylcarbonyl, C₂-C₄ alkyloxycarbonyl, C₂-C₄        alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro;    -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10;    -   X, Y, W, and Z represent independently of each other —CH₂—,        —CH—, —NH— or —N—;    -   represents a single or double bond;    -   and diastereomers, enantiomers, hydrates, and salts thereof;    -   comprising the steps:    -   (A) providing a solution of a compound of formulae (II) in a        polar protic solvent or in a solvent mixture containing a polar        protic solvent containing at least one base

-   -   -   wherein E and p have the meanings as defined above,

    -   (B) providing a solution of a compound of formula (III)

-   -   -   wherein A, B, C, D and R¹ have the meanings as defined            above, and OL represents a leaving group        -   in a polar protic solvent or in a solvent mixture containing            a polar protic solvent;

    -   (C) mixing the solution of the compound of formula (II) and the        solution of the compound of formula (III) and allowing the        compound of formula (II) to react with the compound of        formula (III) in order to obtain the compound of formula (I),

    -   (D) purifying the compound of formula (I) preferably by using        isotonic sodium chloride solution.

-   2. Method according to embodiment 1, wherein step (C) is performed    at a reaction temperature T2 which is in the range of 30° C. to    60° C. and during a reaction time t2 which is 1-30 min and at a pH    value of the reaction solution which is in the range of 7.0-11.0.

-   3. Method according to embodiment 1 or 2, wherein L in the leaving    group OL represents:

-   -   and wherein R⁵ is selected from methyl, ethyl, or n-propyl;

-   4. Method according to embodiments 1, 2 or 3 further comprising the    following step (E) after the step (D):    -   (E) sterilizing the solution of the compound of formula (I) via        steril filtration.

-   5. Method according to embodiments 1, 2, 3 or 4 further comprising    the following steps (A1)-(A8) after step (A) and before step (B):    -   (A1) providing a solution of a compound of the formula (IV) in        at least one polar protic solvent or in a solvent mixture        containing a polar protic solvent,        -   wherein optionally the solution further contains a salt;

-   -   -   wherein        -   A, B, C, D, OL and R¹ have the same meanings as defined in            embodiment 1;        -   X represents NR² ₃, IR³, SR³ ₂;        -   Y represents Br, I, BF₄, O₂CCF₃, OSO₂CF₃, ClO₄, NO₂,            OSO₂C₆H₄CH₃, OSO₂CH₃        -   R² represents C₁-C₄ alkyl; and        -   R³ represents aryl;

    -   (A2) providing an aqueous solution of [¹⁸F]fluoride;

    -   (A3) loading the aqueous solution of [¹⁸F]fluoride onto an anion        exchange resin;

    -   (A4) washing the anion exchange resin with a polar protic        solvent or with a polar aprotic solvent;

    -   (A5) flushing of the solvent with air or inert gas flow;

    -   (A6) eluting of [¹⁸F]fluoride with the solution of the compound        of formula (IV) provided in step (A1) and diluting of the        resulting solution with an aprotic solvent or with at least one        C₃-C₆ alcohol or with a solvent mixture of at least one C₃-C₆        alcohol and an aprotic solvent; or        -   eluting of [¹⁸F]fluoride with the solution of the compound            of formula (IV) provided in step (A1), concentrating of the            resulting solution and redissolving of the residue in an            aprotic solvent;

    -   (A7) allowing the compound of formula (IV) to react with        [¹⁸F]fluoride in order to obtain the compound of the formula        (III);

-   -   -   wherein A, B, C, D, OL and R¹ have the same meanings as            defined in embodiment 1; and

    -   (A8) purifying of the compound of formula (III).

-   6. Method according to any one of the embodiments 1-5 further    comprising the following step (F) after the step (D) or (E):    -   (F) preparing a pharmaceutical composition containing the        solution of the compound of formula (I).

-   7. Method according to any one of the embodiments 1-6, wherein the    base in step (A) is an organic nitrogen-containing base or a    bicarbonate.

-   8. Method according to embodiment 7, wherein the organic    nitrogen-containing base or the bicarbonate is selected from the    group consisting of: LiHCO₃, NaHCO₃, KHCO₃, CsHCO₃, Me₄NHCO₃,    Et₄NHCO₃, n-Pr₄NHCO₃, i-Pr₄NHCO₃, n-Bu₄NHCO₃, i-Bu₄NHCO₃, Et₃N,    pyridine, lutidine, collidine, diisopropylethylamine, n-Pr₃N,    i-Pr₃N, n-Bu₃N, i-Bu₃N, Oct₃N, N-methyl-morpholine,    N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine,    N,N-dicyclohexylmethylamine, N,N-dimethylcyclohexylamine,    N-methyl-dibutylamine, N-ethyldicyclohexylamine,    N,N-dimethylbutylamine, and N,N-dimethylhexylamine

-   9. Method according to any one of the embodiments 1-8, wherein the    polar protic solvent is an anhydrous polar protic solvent,    especially anhydrous MeOH or anhydrous EtOH or a mixture thereof.

-   10. Method according to any one of the embodiments 1-9, wherein the    compound (III) is

-   11. Method according to any one of the embodiments 5-10, wherein the    [¹⁸F]fluoride is trapped on an anion exchange resin and then eluted    directly.-   12. Method according to any one of the embodiments 5-11, wherein the    C₃-C₆ alcohol is tBuOH.-   13. Method according to any one of the embodiments 1-12, wherein the    compound of the formula (I) is selected from the group consisting of    compounds 1-3, 1-10, 1-14, 1-17, 1-29, 1-31, 1-32, 1-33, and 1-34:

-   14. Pharmaceutical composition containing at least one compound of    formula (I) as defined in embodiment 1 together with at least one    pharmaceutically acceptable solvent, ingredient and/or diluent.-   15. Pharmaceutical composition according to embodiment 14 for use in    imaging prostate cancer cells or prostate cancerous tissue.-   16. A method for preparing a compound of formula (I)

-   -   wherein    -   A, B, C, and D represent independently of each other C—H, C—F or        N;    -   and not more than two of A, B, C, and D represent N;    -   E represents a covalent bond or

-   -   R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₄        alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro;    -   n is an integer selected from 0 to 10;    -   m is an integer selected from 1 to 18;    -   p is an integer selected from 0 to 10;    -   X, Y, W, and Z represent independently of each other —CH₂—, C—H,        —NH— or N;    -   represents a single or double bond;    -   and diastereomers, enantiomers, hydrates, and salts thereof;    -   comprising the steps:    -   (A) providing a solution of a compound of formulae (II) in a        polar protic solvent or in a solvent mixture containing a polar        protic solvent containing at least one base

-   -   -   wherein E and p have the meanings as defined above,

    -   (B) providing a solution of a compound of formula (III)

-   -   -   wherein        -   A, B, C, D and R¹ have the meanings as defined above, and        -   OL represents a leaving group        -   in a polar protic solvent or in a solvent mixture containing            a polar protic solvent;

    -   (C) mixing the solution of the compound of formula (II) and the        solution of the compound of formula (III) and allowing the        compound of formula (II) to react with the compound of        formula (III) in order to obtain the compound of formula (I),

    -   (D) purifying the compound of formula (I).

-   17. Method according to embodiment 16, wherein step (C) is performed    at a reaction temperature T2 which is in the range of 30° C. to    60° C. and during a reaction time t2 which is 1-30 min and at a pH    value of the reaction solution which is in the range of 7.0-11.0.

-   18. Method according to embodiment 16 or 17, wherein L in the    leaving group OL represents:

-   -   and wherein R⁵ is selected from methyl, ethyl, or n-propyl;

-   19. Method according to any one of embodiments 16 to 18 further    comprising the following step (E) after the step (D):    -   (E) sterilizing the solution of the compound of formula (I) via        sterile filtration.

-   20. Method according to any one of embodiments 16 to 19 further    comprising the following steps (A1)-(A8) after step (A) and before    step (B):    -   (A1) providing a solution of a compound of the formula (IV) in        at least one polar protic solvent or in a solvent mixture        containing a polar protic solvent,        -   wherein optionally the solution further contains a salt;

-   -   -   wherein        -   A, B, C, D, OL and R¹ have the same meanings as defined in            claim 1;        -   X represents NR² ₃, IR³, SR³ ₂;        -   Y represents Br, I, BF₄, O₂CCF₃, OSO₂CF₃, ClO₄, NO₂,            OSO₂C₆H₄CH₃, OSO₂CH₃        -   R² represents C₁-C₄ alkyl; and        -   R³ represents aryl;

    -   (A2) providing an aqueous solution of [¹⁸F]fluoride;

    -   (A3) loading the aqueous solution of [¹⁸F]fluoride onto an anion        exchange resin;

    -   (A4) washing the anion exchange resin with a polar protic        solvent or with a polar aprotic solvent;

    -   (A5) flushing of the solvent with air or inert gas flow;

    -   (A6) eluting of [¹⁸F]fluoride with the solution of the compound        of formula (IV) provided in step (A1) and diluting of the        resulting solution with an aprotic solvent or with at least one        C₃-C₆ alcohol or with a solvent mixture of at least one C₃-C₆        alcohol and an aprotic solvent;        -   or        -   eluting of [¹⁸F]fluoride with the solution of the compound            of formula (IV) provided in step (A1), concentrating of the            resulting solution and redissolving of the residue in an            aprotic solvent;

    -   (A7) allowing the compound of formula (IV) to react with        [¹⁸F]fluoride in order to obtain the compound of the formula        (III);

-   -   -   wherein A, B, C, D, OL and R¹ have the same meanings as            defined in claim 1; and

    -   (A8) purifying of the compound of formula (III).

-   21. Method according to any one of the embodiments 16-20 further    comprising the following step (F) after the step (D) or (E):    -   (F) preparing a pharmaceutical composition containing the        solution of the compound of formula (I).

-   22. Method according to any one of the embodiments 16 to 21, wherein    the base in step (A) is selected from the group consisting of:    -   LiHCO₃, NaHCO₃, KHCO₃, CsHCO₃, Me₄NHCO₃, Et₄NHCO₃, n-Pr₄NHCO₃,        n-Bu₄NHCO₃, Et₃N, pyridine, lutidine, collidine,        diisopropylethylamine, n-Bu₃N, Oct₃N, N-methylmorpholine,        N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine,        N,N-dicyclohexylmethylamine, N,N-dimethylcyclohexylamine,        N-methyldibutylamine, N-ethyldicyclohexylamine,        N,N-dimethylbutylamine, and N,N-dimethylhexylamine.

-   23. Method according to any one of the embodiments 16 to 22, wherein    the polar protic solvent is MeOH or EtOH.

-   24. Method according to any one of the embodiments 16 to 23, wherein    the compound (III) is

-   25. Method according to any one of the embodiments 20-24, wherein    the [¹⁸F]fluoride is trapped on an anion exchange resin and then    eluted directly.-   26. Method according to any one of the embodiments 20-24, wherein    the C₃-C₆ alcohol is tBuOH.-   27. Method according to any one of the embodiments 16-26, wherein    the compound of the formula (I) is selected from the group    consisting of compounds 1-3, 1-10, 1-14, 1-17, 1-29, 1-31, 1-32,    1-33, and 1-34:

-   28. Pharmaceutical composition containing at least one compound of    formula (I) as defined in embodiment 16 together with at least one    pharmaceutically acceptable solvent, ingredient and/or diluent.-   29. Pharmaceutical composition according to embodiment 28 for use in    imaging prostate cancer cells or prostate cancerous tissue.

The invention claimed is:
 1. A compound of formula (II)

wherein, E represents a covalent bond or

wherein n is an integer selected from 0 to 10; n₁ is an integer selectedfrom 0 to 10; n₂ is an integer selected from 0 to 10; m is an integerselected from 1 to 18; p is an integer selected from 0 to 10; q is aninteger selected from 1 to 18; X, Y, W, and Z represent independently ofeach other —CH₂—, —CH—, —NH— or —N—;

represents a single or double bond; and diastereomers, entantiomers,hydrates, and salts thereof.
 2. A compound of formula (II)

wherein, E represents a covalent bond or

wherein n is an integer selected from 0 to 10; m is an integer selectedfrom 1 to 18; X, Y, W, and Z represent independently of each other—CH₂—, —CH—, —NH— or —N—;

represents a single or double bond; and diastereomers, entantiomers,hydrates, and salts thereof.
 3. A compound according to claim 1, whereinsaid compound is a direct precursor of the compound of formula (I)

wherein A, B, C, and D represent independently of each other C—H, C—F,C—Cl, or N; and not more than two of A, B, C, and D represent N; Erepresents a covalent bond or

wherein R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃thioalkyl, perfluoralkyl, C₁-C₃ haloalkoxy, C₁-C₄ alkylcarbonyl, C₁-C₄alkyloxycarbonyl, C₁-C₄alkylcarboxy, aryloxy, alkylaryl, aryl,arylcarboxy, halogen; n is an integer selected from 0 to 10; n₁ is aninteger selected from 0 to 10; n₂ is an integer selected from 0 to 10; mis an integer selected from 1 to 18; p is an integer selected from 0 to10; q is an integer selected from 1 to 18; X, Y, W, and Z representindependently of each other —CH₂—, —CH—, —NH—, or —N;

represents a single or double bond; and diastereomers, entantiomers,hydrates, and salts thereof.
 4. The compound according to claim 3,wherein the compound is a direct precursor of the compound of formula(I) of claim 3,

wherein A, B, C, and D represent independently of each other C—H, C—F orN; and not more than two of A, B, C, and D represent N; E represents acovalent bond or

wherein R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃haloalkoxy, C₂-C₄ alkylcarbonyl, C₂-C₄ alkyloxycarbonyl, C₂-C₄alkylcarboxy, aryloxy, arylcarboxy, cyano, or nitro; n is an integerselected from 0 to 10; m is an integer selected from 1 to 18; X, Y, W,and Z represent independently of each other —CH₂—, —CH—, —NH— or —N—;

represents a single or double bond; and diastereomers, entantiomers,hydrates, and salts thereof.
 5. The compound according to claim 1,wherein either of n or n₁ or n₂ is an integer selected from 1 to
 4. 6.The compound according to claim 1, wherein either of n or n₁ or n₂ is aninteger selected from 1 or
 2. 7. The compound according to claim 1,wherein either of m is an integer selected from 1 to
 10. 8. The compoundaccording to claim 1, wherein either of m is an integer selected from 1to
 4. 9. The compound according to claim 1, wherein either of p is aninteger selected from 0 to
 6. 10. The compound according to claim 1,wherein either of p is an integer selected from 0, 2 to
 4. 11. Thecompound according to claim 1, wherein either of q is an integerselected from 1 to
 10. 12. The compound according to claim 1, whereineither of q is an integer selected from 1 to
 3. 13. A compound accordingto claim 1 selected from compounds 2a-2p:


14. The compound according to claim 1, wherein the salt is selected fromacetate, trifluoroacetate, tosylate, mesylate, triflate, chloride,bromide, iodide, sulfate, hydrosulfate, nitrate, perchlorate, lithium,sodium, potassium, cesium, trialkylaryl-, tetraaryl-, tri- andtetralkylammonium salts.
 15. A compound according to claim 3, whereinthe direct precursor of the compound of formula (I) is capable of beingcoupled to a compound of formula (II), optionally in an anhydrous proticsolvent, wherein formula (III) is

wherein A, B, C, D and R¹ have the meanings as defined, and OLrepresents a leaving group.
 16. A method of preparing a compound (III)

wherein A, B, C, and D represent independently of each other C—H, C—F,C—Cl, or N; and not more than two of A, B, C, and D represent N; and R¹represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, —C₁-C₃ thioalkyl,perfluoralkyl, C₁-C₃ haloalkoxy, C₁-C₄ alkylcarbonyl, C₁-C₄alkyloxycarbonyl, C₁-C₄ alkylcarboxy, aryloxy, alkylaryl, aryl,arylcarboxy, halogen; and OL represents a leaving group comprising thefollowing steps (A1)-(A8): (A1) providing a solution of a compound ofthe formula (IV) in at least one polar protic solvent or in a solventmixture containing a polar protic solvent,

wherein A, B, C, D, OL and R¹ have the same meanings as defined above; Xrepresents NR² ₃, IR³, or SR³ ₂; Y represents Br, I, BF₄, O₂CCF₃,OSO₂CF₃, ClO₄, NO₂, OSO₂C₆H₄CH₃, or OSO₂CH₃, R² represents C₁-C₄ alkyl;and R³ represents aryl; (A2) providing an aqueous solution of[¹⁸F]fluoride; (A3) loading the aqueous solution of [¹⁸F]fluoride ontoan anion exchange resin; (A4) washing the anion exchange resin with apolar protic solvent or with a polar aprotic solvent; (A5) flushing ofthe solvent with air or inert gas flow; (A6) eluting of [¹⁸F]fluoridewith the solution of the compound of formula (IV) provided in step (A1)and diluting of the resulting solution with an aprotic solvent or withat least one C₃-C₆ alcohol or with a solvent mixture of at least oneC₃-C₆ alcohol; or eluting of [¹⁸F]fluoride with the solution of thecompound of formula (IV) provided in step (A1) concentrating of theresulting solution and redissolving of the residue in an aproticsolvent; (A7) allowing the compound of formula (IV) to react with[¹⁸F]fluoride in order to obtain the compound of the formula (III);

wherein A, B, C, D, OL and R¹ have the same meanings as defined above;and (A8) purifying of the compound of formula (III).
 17. A method forpreparing a compound of formula (I) which comprises using a compound offormula (II) as defined in claim 1 in the method:

wherein A, B, C, and D represent independently of each other C—H, C—F,C—Cl, or N; and not more than two of A, B, C, and D represent N; Erepresents a covalent bond or

wherein R¹ represents C₁-C₃ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃thioalkyl, perfluoralkyl, C₁-C₃ haloalkoxy, C₁-C₄ alkylcarbonyl, C₁-C₄alkyloxycarbonyl, C₁-C₄alkylcarboxy, aryloxy, alkylaryl, aryl,arylcarboxy, halogen; n is an integer selected from 0 to 10; n₁ is aninteger selected from 0 to 10; n₂ is an integer selected from 0 to 10; mis an integer selected from 1 to 18; p is an integer selected from 0 to10; q is an integer selected from 1 to 18; X, Y, W, and Z representindependently of each other —CH₂—, —CH—, —NH—, or —N;

represents a single or double bond; and diastereomers, entantiomers,hydrates, and salts thereof.
 18. A method for preparing a compound offormula (I) as defined in claim 3,

comprising the steps: (A) providing a solution of a compound of formula(II) in a polar protic solvent or in a solvent mixture containing apolar protic solvent containing at least one base;

(B) providing a solution of a compound of formula (III)

wherein A, B, C, D and R¹ have the meanings as defined, and OLrepresents a leaving group in a polar protic solvent or in a solventmixture containing a polar protic solvent; (C) mixing the solution ofthe compound of formula (II) and the solution of the compound of formula(III) and allowing the compound of formula (II) to react with thecompound of formula (III) in order to obtain the compound of formula(I), (D) purifying the compound of formula (I).
 19. Method according toclaim 18, wherein step (C) is performed at a reaction temperature T2which is in the range of 30° C. to 60° C., wherein the reaction time t2of step (C) is 1-30 min, and wherein the pH value of the reactionsolution in step (C) is in the range of 7.0-11.0.
 20. Method accordingto claim 18, wherein the compound of formula (III) does not requirepurification via HPLC, and/or wherein the method does not comprise theapplication of a base and any other additives; and/or wherein the methodcomprises the application of only onium salt precursor (IV) and[¹⁸F]fluoride; and/or wherein the method does not comprise anyazeotropic drying steps; and/or wherein the method does not require anyevaporation steps.
 21. Method according to claim 18, wherein thecompound of formula (I) does not require purification via HPLC, andwherein the method comprises the application of environmentally benignsolvents; and/or wherein the method does not comprise any evaporationsteps, and/or wherein the method does not require any deprotectionsteps, wherein said deprotection steps may be steps of p-methoxybenzyl(PMB) or tBu deprotection using anisol/TFA mixture; and/or wherein themethod does not require a neutralization step; and/or wherein the methoddoes not require a formulation step, and/or wherein the method does notrequire toxic solvents.
 22. Method according to claim 18 furthercomprising the following step (E) after the step (D): (E) sterilizingthe solution of the compound of formula (I) via sterile filtration. 23.Method according to claim 18 further comprising the following steps(A1)-(A8) after step (A) and before step (B): (A1) providing a solutionof a compound of the formula (IV) in at least one polar protic solventor in a solvent mixture containing a polar protic solvent,

wherein A, B, C, D, OL and R¹ have the same meanings as defined above; Xrepresents NR² ₃, IR³, or SR³ ₂; Y represents Br, I, BF₄, O₂CCF₃,OSO₂CF₃, ClO₄, NO₂, OSO₂C₆H₄CH₃, or OSO₂CH₃; R² represents C₁-C₄ alkyl;and R³ represents aryl; (A2) providing an aqueous solution of[¹⁸F]fluoride; (A3) loading the aqueous solution of [¹⁸F]fluoride ontoan anion exchange resin; (A4) washing the anion exchange resin with apolar protic solvent or with a polar aprotic solvent; (A5) flushing ofthe solvent with air or inert gas flow; (A6) eluting of [¹⁸F]fluoridewith the solution of the compound of formula (IV) provided in step (A1)and diluting of the resulting solution with an aprotic solvent or withat least one C₃-C₆ alcohol or with a solvent mixture of at least oneC₃-C₆ alcohol; or eluting of [¹⁸F]fluoride with the solution of thecompound of formula (IV) provided in step (A1) concentrating of theresulting solution and redissolving of the residue in an aproticsolvent; (A7) allowing the compound of formula (IV) to react with[¹⁸F]fluoride in order to obtain the compound of the formula (II);

wherein A, B, C, D, OL and R¹ have the same meanings as defined above;and (A8) purifying of the compound of formula (III).
 24. Methodaccording to claim 18 further comprising the following step (F) afterthe step (D) or (E): (F) preparing a pharmaceutical compositioncontaining the solution of the compound of formula (I).
 25. Methodaccording to claim 18, wherein the base in step (A) is an organicnitrogen-containing base or a bicarbonate.
 26. Method according to claim25, wherein the organic nitrogen-containing base or the bicarbonate isselected from: LiHCO₃, NaHCO₃, KHCO₃, CsHCO₃, Me₄NHCO₃, Me₄NHPO₄,Et₄NHCO₃, Et₄NHPO₄, n-Pr₄NHCO₃, n-Pr₄NHPO₄, i-Pr₄NHCO₃, n-Bu₄NHCO₃,n-Bu₄NHPO₄, BzlMe₃NHCO₃, BzlMe₃NHPO₄, BzlEt₃NHCO₃, BzlEt₃NHPO₄,BzlBu₃NHCO₃, BzlBu₃NHPO₄, Et₃N, pyridine, lutidine, collidine,diisopropylethylamine, n-Pr₃N, i-Pr₃N, n-Bu₃N, i-Bu₃N, Oct₃N,N-methyl-morpholine, N-ethylmorpholine, N-methylpiperidine,N-ethylpiperidine, N,N-dicyclohexylmethylamineN,N-dimethylcyclohexylamine, N-methyl-dibutylamine,N-ethyldicyclohexylamine, N,N-dimethylbutylamine, andN,N-dimethylhexylamine.
 27. Method according to claim 18, wherein thepolar protic solvent in step A6 is an anhydrous polar protic solvent inmethods without evaporation step, or anhydrous MeOH in methodscomprising an evaporation step.
 28. Method according to claim 18,wherein the [¹⁸F]fluoride is trapped on an anion exchange resin and theneluted directly.
 29. Method according to claim 18, wherein the C₃-C₆alcohol is tBuOH, tertAmOH, or pinacol.
 30. Method according to claim18, wherein the compound of the formula (I) is selected from the groupconsisting of compounds 1-10, 1-14, 1-17, 1-29, 1-31, 1-32, 1-33, and1-34:


31. A kit for carrying out the method of claim 18 comprising one or morecontainers containing the compounds of formula (II) and (Ill),optionally a packaged pharmaceutical compositions comprising apharmaceutically acceptable carrier, further optionally comprisinginstructions for preparing compounds according to the invention fromsupplied precursors and/or instructions for using the composition toimage cells or tissues.
 32. The method of claim 16, wherein the compoundof formula (III) is of formula 3c, 3d, 3e or 3f:


33. The method of claim 18, wherein the compound of formula (III) is offormula 3c, 3d, 3e or 3f:


34. The method of claim 15, wherein the compound of formula (III) is offormula 3c, 3d, 3e or 3f:


35. The method of claim 15, wherein: the anhydrous protic solvent is aC₂-C₅ alcohol; wherein the residue L of the leaving group OL in formula(III) represents:

and wherein R⁵ is selected from methyl, ethyl or n-propyl.